KERMIT USER GUIDE Fifth Edition, Revision 1 Frank da Cruz, editor

KERMIT USER GUIDE Fifth Edition, Revision 1 Frank da Cruz, editor

KERMIT USER GUIDE

Fifth Edition, Revision 1

Frank da Cruz, editor

Columbia University Center for Computing Activities

New York, New York 10027

27 July 1984

Copyright (C) 1981,1982,1983,1984

Trustees of Columbia University in the City of New York

Permission is granted to any individual or institution to copy or

use this document and the programs described in it, except for

explicitly commercial purposes.

Preface to the 5th Edition Page 1

Preface to the 5th Edition (March 1984)

Since the 4th Edition of the KERMIT Users Guide was produced in July

1983, the KERMITs have been flying thicker and faster than anyone could keep up with. Old versions have improved, and implementations for many new systems have appeared. It is no longer practical to even attempt to cover all the implementations in a single manual. Therefore, this manual will try to describe a sort of "ideal" KERMIT program, one which has most of the features specified in the KERMIT Protocol Manual. Most real KERMIT programs will fall short of this description in some ways.

After the main, system-independent part of the manual there are sections for several particular KERMIT programs, emphasizing their differences from the ideal, at the time of this writing. The system-dependent por- tions of this manual will rapidly become dated; current information about any particular KERMIT program can be found in the accompanying on-line help or documentation files, or built-in internal help text.

5TH EDITION, REVISION 1 (July 1984)

The major sections of the manual are relatively unchanged. The chapters describing DECSYSTEM-20, MS-DOS, CP/M-86, CP/M-80, and Apple DOS Kermits have been updated to reflect new releases since last March. Meanwhile, a 2-part article describing the Kermit protocol was published in the

June and July 1984 issues of BYTE Magazine, which is recommended reading for anyone who wants to know the reasons why a protocol like Kermit is necessary.

HISTORY AND ACKNOWLEDGEMENTS

The KERMIT file transfer protocol was designed at the Columbia Univer- sity Center for Computing Activities (CUCCA) in 1981-82 mainly by Bill

Catchings and Frank da Cruz. Bill wrote the first two programs, one for the DECSYSTEM-20 and one for a CP/M-80 microcomputer.

The initial objective was to allow users of our DEC-20 and IBM timeshar- ing systems to archive their files on microcomputer floppy disks. The design owes much to the ANSI and ISO models, and ideas were borrowed from similar projects at Stanford University and the University of Utah.

The protocol was designed to accommodate the "sensitive" communications front end of the full-duplex DEC-20 system as well as the peculiarities of half-duplex IBM mainframe communications. The protocol was soon im- plemented successfully on our IBM 4341 systems under VM/CMS by Daphne

Tzoar of CUCCA.

Meanwhile it was becoming apparent that KERMIT was useful for more than just file archiving; IBM PCs were beginning to appear in the offices and departments, and there arose a general need for file transfer among all our systems. Daphne soon had prepared an IBM PC implementation.

After our initial success with KERMIT, we presented it at conferences of user groups like DECUS and SHARE, and we began to get requests for it from other sites. Since we had written down a description of the

protocol, some sites wrote their own implementations for new computers, or adapted one of our implementations to run on additional systems, and sent back these new versions to us so that we could share them with

Preface to the 5th Edition Page 2 others. In this way, KERMIT has grown to support about 50 different systems; it has been sent on magnetic tape from Columbia to hundreds of sites in dozens of countries, and has reached hundreds or thousands more through various user groups and networks.

To date, contributions to the KERMIT effort have been made by in- dividuals at the following institutions: Stevens Institute of Technol- ogy, Cornell University, Rutgers University, Cerritos College, the

University of Toronto, the University of Tennessee at Knoxville, the

University of California at Berkeley, the University of Toledo, the

University of Texas at Austin, the University of Michigan, Oakland

University, the University of Wisconsin, University College Dublin, the

University of Washington, ABC-Klubben Stockholm, the Helsinki University of Technology, the US National Institutes of Health, Digital Equipment

Corporation, The SOURCE Telecomputing, Hewlett-Packard Laboratories,

Litton Data Systems, RCA Laboratories, Atari Computer, the University of

Chicago, SPSS Inc, and others. The list grows constantly.

The Kermit protocol was named after Kermit the Frog, start of the television series THE MUPPET SHOW, and is used by permission of Henson

Associates, Inc.

CUSTOMIZING THIS MANUAL

Although this manual was produced at Columbia University, all attempts have been made to keep it free of site-specific information. However, due to the large number of KERMIT implementations, descriptions of each one would make the manual unnecessarily thick. Therefore, the manual is sent from Columbia with specific documentation about a selection of sys- tems. Some of these descriptions may not be of interest at your site, while others that are may be lacking.

Each site, upon receiving a KERMIT tape, may decide which versions of

KERMIT are important to it, and include the appropriate documentation in this manual. This is most conveniently done if your site has the Scribe text formatting system (from UNILOGIC Ltd in Pittsburgh PA, USA), with which this manual was produced. Scribe runs on a wide variety of sys- tems. There are also Scribe subsets, such as Perfect Writer and Final

Word, that run on various microcomputers.

The system-specific parts of the KERMIT User Guide are included with

"@INCLUDE" statements at the end of the Scribe source file for this manual, whose filename is USER.MSS. You may add or delete @INCLUDE statements to suit your needs, and run the result through the text for- matter to produce a customized manual.

Not all system-specific documentation is provided in .MSS (Scribe input) format, since some KERMIT contributors do not have Scribe at their sites. In that case, you will either have to add Scribe formatting com- mands, or else enclose the whole subfile in @VERBATIM brackets.

If you do not have SCRIBE, you may still use an editor to delete or add sections to the finished documentation file, though the results will not be as satisfactory -- the table of contents, index, and page numbers will not be automatically adjusted.

Preface to the 5th Edition Page 3

If you are running a version of KERMIT for which adequate documentation has not been provided (after all, this is a distributed, volunteer ef- fort!), please feel free to write some, preferably in Scribe input for- mat, and send it back to Columbia so that others may benefit from it.

Likewise if you produce a new implementation of KERMIT.

Ordering Information Page 4

Ordering Information

The KERMIT software is free and available to all. Columbia University, however, cannot afford to distribute free software on the scale required for KERMIT. Therefore, to defray our costs for media, printing, pos- tage, materials, labor, and computing resources, we must request a moderate distribution fee from sites that request KERMIT directly from

Columbia. The schedule is as follows:

Complete KERMIT Distribution $100.00

(Tape, Users Guide, and Protocol Manual)

Printed Documents $5.00 each

(Users Guide, Protocol Manual, or Any Source Listing)

Other sites are free to redistribute KERMIT on their own terms, and are encouraged to do so, with the following stipulations: KERMIT should not be sold for profit; credit should be given where it is due; and new material should be sent back to Columbia University at the address below so that we can maintain a definitive and comprehensive set of KERMIT im- plementations for further distribution.

To order KERMIT from Columbia University, send a letter requesting ei- ther:

(a) The manuals or source listings you desire (specify each one), or

(b) A 9-track magnetic tape in one of the following formats:

System Tape Format Densities

TOPS-10 BACKUP/Interchange, Unlabeled 1600

TOPS-20 DUMPER, Unlabeled 1600

IBM VM/CMS EBCDIC, CMS Format 1600, 6250

or EBCDIC, OS Standard Label 1600, 6250

UNIX TAR 1600

Other ASCII, ANSI Label, Format ``D'' 1600

(Specify system, format, and density.) The "Kermit collection"

has grown so large that we can no longer fit it on a 2400' reel of

magnetic tape at 800bpi. One copy of each manual will be included

with the tape. We will supply the tape, packaging, and postage.

We can only make tapes in the formats listed above. We cannot produce floppy disks; bootstrapping procedures are provided to allow the microcomputer versions to be downloaded from the mainframe for which the tape is produced. The tape includes all source programs, documentation, and, when practical, binaries or hex. Unfortunately, our limited resources to not allow us to provide automatic updates to KERMIT recipients when new implementations, documentation, or bug fixes appear.

Send your letter to:

KERMIT Distribution

Columbia University Center for Computing Activities

7th Floor, Watson Laboratory

612 West 115th Street

Ordering Information Page 5

New York, N.Y. 10025

Please list the machines and operating systems you expect to run KERMIT on, specify the tape format or the listings desired, and mention whether there are additional systems for which you require KERMIT or if you might be interested in attempting your own implementation for a new sys- tem. Make checks payable to Columbia University Center for Computing

Activities.

KERMIT is available to users of the BITNET network via a server at host

CUVMA. BITNET users may type ``SMSG RSCS MSG CUVMA KERMSRV HELP'' for further information. KERMIT is also available to users of ARPANET, via anonymous FTP from host COLUMBIA-20, in the area PS:<KERMIT>. And KER-

MIT is distributed regularly by various computer user groups such as

DECUS and SHARE.

Since new KERMIT programs are added -- and old ones improved -- so fre- quently, sites that use KERMIT heavily are encouraged to contact Colum- bia two or three times a year for news.

No warranty of the software nor of the accuracy of the documentation surrounding it is expressed or implied, and neither the authors nor

Columbia University acknowledge any liability resulting from program or documentation errors.

Introduction Page 6

1. Introduction

Everyone wants to get computers talking to one another. There are many ways to do this, and most of them are very expensive. But there is one way that is cheap and relatively easy: connect the two computers through their terminal (TTY) ports, tricking one computer (or both) into believ- ing that the other is a terminal. This can be expected to work because the standard for connecting computers to terminals is almost universally followed, in both hardware (plug and signal: EIA RS-232) and software

(character code: ASCII). Once two computers are connected in this way, cooperating programs can be run on each to achieve the desired com- munication by means of a communication protocol.

Why is a protocol necessary at all? Three major problems occur when you try to connect two computers via TTY line:

1. Noise -- It is rarely safe to assume that there will be no

electrical interference on a line; any long or switched data

communication line will have occasional interference, or

noise, which typically results in garbled or extra charac-

ters. Noise corrupts data, perhaps in subtle ways that might

not be noticed until it's too late.

2. Synchronization -- Data must not come in faster than the

receiving machine can handle it. Although line speeds at the

two ends of the connection may match, the receiving machine

might not be able to process a steady stream of input at that

speed. Its central processor may be too slow or too heavily

loaded, or its buffers too full or too small. The typical

symptom of a synchronization problem is lost data; most

operating systems will simply discard incoming data they are

not prepared to receive.

3. Line Outages -- A line may stop working for short periods be-

cause of a faulty connector, loss of power, or similar

reason. On dialup or switched connections, such intermittent

failures will cause carrier to drop and the connection to be

closed, but for any connection in which the carrier signal is

not used, the symptom will be lost data.

To prevent corruption of data and to synchronize communication, cooperating computers can send control information to one another at the same time that they are transferring data. This intermingling of con- trol information with data, and the resulting actions, constitute a

"protocol".

KERMIT is such a protocol. It is specifically designed for transfer of sequential files over ordinary serial telecommunication lines. KERMIT is not necessarily better than many other terminal-oriented file trans- fer protocols but it is free, it is well documented, and it has been im- plemented compatibly on a variety of microcomputers and mainframes.

KERMIT transfers data by encapsulating it in "packets" of control infor- mation. This information includes a synchronization marker, a packet number to allow detection of lost packets, a length indicator, and a

"checksum" to allow verification of the data. Lost or corrupt packets

Introduction Page 7 are detected, and retransmission is requested. Duplicated packets are discarded. In addition, various special control packets allow cooperat- ing KERMITs to connect and disconnect from each other and to exchange various kinds of information. Very few assumptions are made about the capabilities of either computer, so the KERMIT protocol can work between many different kinds of systems.

ORGANIZATION OF THIS MANUAL

Section 2, How to Use KERMIT, tells all you need to know to transfer text files in most cases, and shows some specific examples.

If you follow the examples in Section 2 but you can't make a terminal connection or you can't transfer files successfully, consult Section 3,

When Things Go Wrong.

If you expect to be a heavy user of KERMIT, you should read Section 4,

KERMIT Commands, which describes all the features of KERMIT in detail.

You may find that familiarity with the material in this section will help you get past difficulties that can crop up when you are making new kinds of connections or transferring unusual kinds of files. You will also find descriptions of some advanced file management features that have been omitted from the earlier sections.

Section 5, KERMIT Implementations, briefly lists the systems for which

KERMIT is available as of this writing. The subsequent chapters describe selected particular implementations. You should read the ap- propriate section for each system with which you are using KERMIT; each section describes the file naming conventions and other system features that are important to KERMIT users, and lists the KERMIT commands for that system mainly in terms of their differences from the "ideal" KERMIT described in section 4.

How to Use KERMIT Page 8

2. How to Use KERMIT

KERMIT is a protocol for reliable file transfer between computers over the ordinary serial telecommunication lines that are used to connect terminals to computers. The mechanics of using KERMIT to get a file transferred can be confusing until you get the hang of it. A little background material might make the process a bit easier to understand.

KERMIT is probably the cheapest way to put two computers into communica- tion. The required hardware is usually already available, the software is free, and all components run as ordinary user programs, with no sys- tem modifications. This is in sharp contrast to a communication net- work, where there are dedicated high-speed communications channels and drivers, expensive software, and so forth. The network provides more services than KERMIT, usually at higher speed, and with greater con- venience, because the network is usually part of the system. When a network is not available, KERMIT can fill in. But since KERMIT is not integrated with any particular system, but rather grafted on top of many different systems, it requires some extra work from those who use it.

2.1. The KERMIT Program

KERMIT embodies a set of rules for transferring files reliably between computers. In general, one computer is a large system (a host, for in- stance a timesharing system with many terminals), and the other is a

1 personal computer (PC) . The host believes that the PC is an ordinary terminal. In order for the KERMIT protocol to occur, a KERMIT program must be running on each end of the communication line -- one on the host, one on the PC.

The two Kermit programs exchange messages in a special language all their own, the Kermit protocol. The dialog runs something like, "Hi!

I'm going to be sending files to you. When you send messages to me, please don't make them more than 80 characters long, and if you don't hear anything from me for 15 seconds, wake me up, OK?" "OK." "Now, here comes a file called FOO.TXT, OK?" "OK." "Here's the first piece..."

"Got it." "Good, here's the second piece..." "That second piece was junk." "Well, then here it is again..." Et cetera. You don't see any of this. It's all packed into a concise code which the two Kermits can understand; they do all the worrying about transmission, error checking, character set translation, and so forth. Each message is called a packet, and each packet is in a special format that all Kermits can un- derstand.

_______________

1

Host-to-host and PC-to-PC connections are also possible.

How to Use KERMIT Page 9

2.2. Talking to Two Computers at Once

Your task is just to get the two Kermits started. The confusion arises because you have to use a single keyboard and screen to talk to two dif- ferent computers, two different programs. Let's talk about a common

2 case: you are sitting at a personal computer (PC ), which has a serial communication port. The serial port is connected to a host computer

3 using, say, a dialup modem .

Normally, when you use your PC, you are "talking" directly to it; your commands are interpreted directly by the PC's operating system (CP/M,

MS-DOS, UNIX, whatever), or by some program that runs on the PC (an editor, a text formatter, space invaders...). The version of Kermit on your PC is a program like any other, but it has a special ability to ei- ther interpret your commands directly, like other programs, or to pass everything you type through to the host. When you tell Kermit to

CONNECT, it sends every character you type out the serial port, and it will put every character that comes in the serial port onto the screen.

This is called virtual terminal service -- one computer acts "virtually" as though it were a terminal on another. You are now "talking" to the host, and the PC is ignoring you.

Kermit, like most programs, has a prompt. The prompt is a symbol it types on the left margin to indicate that it is ready for you to type a command. Kermit's prompt is normally "Kermit-xx>". The xx identifies the implementation of Kermit; the Kermit that runs on the DEC-20 is called "Kermit-20" and its prompt is "Kermit-20>"; the Kermit that runs on Z80 and 8080-based microcomputers is called "Kermit-80" and its

4 prompt is "Kermit-80>"; the Kermit on the IBM PC is "Kermit-86" , and so forth. If you become confused about who you are talking to, the prompt should provide a clue. In addition, most Kermits print an informative message like

[Connecting to remote host, type CTRL-]C to return] when you CONNECT, and type another message like

[Connection closed, back at PC]

_______________

2

The terms PC, micro, microcomputer, and workstation will all be used loosely in this document to denote a single-user system.

3

The actual means of connection isn't important in this case -- it also could be a direct line to the host, some kind of switched line,

etc.

4

Although the processor in the IBM PC is an 8088, it is programmed as though it were an 8086.

How to Use KERMIT Page 10 when you return.

Having "connected" to the host, there must be a way for you to get back to the PC. This is accomplished by an escape sequence. As Kermit passes your characters through to the host, it checks each one to see if it's a special predefined escape character. When the PC sees this character, it stops ignoring you -- you are once again "talking" to the

PC, not the host. The escape character is normally chosen to be one that you will not need to type while talking to the host, and one that is hard to type by accident -- it's usually a control character, such as

Control-], which is accomplished by holding down the key marked CTRL or

CONTROL and typing the indicated character (in this case, a right bracket "]"). The CTRL key works just like a SHIFT key. Control characters are written either as CTRL-A or ^A, where A is the character to be typed while holding down CTRL.

2.3. Transferring a File

To transfer a file, you must first get the attention of the PC's operat- ing system. This is normally done by starting the PC, possibly insert- ing your system floppy disk first. Once you're at command level on your

PC, you run Kermit. Then you tell Kermit to CONNECT you to the host.

Now you're talking to the host -- at this point you must log in, and then run Kermit on the host.

Now you have a Kermit on each end of the wire. The next step is to tell each Kermit what to do. Suppose you want to transfer a file from the host to the PC; you would first tell the host Kermit to SEND the file, then "escape" back to the PC Kermit and tell it to receive the file.

The transfer begins -- you can sit back and watch, or go make yourself a sandwich. The PC Kermit will continuously show packet and retry counts on your screen, and will notify you when the transfer is complete.

The desired file is now on your PC's disk. The Kermit protocol has en- sured that the file arrived correctly and completely. Now you must clean up after yourself: CONNECT back to the host, exit from Kermit on the host, log out from the host, "escape" back to PC Kermit and exit from it. Now you can do whatever you had planned for your file -- edit it, print it on your PC printer, etc.

The KERMIT protocol, and most Kermit programs, allow you to send a file reliably from the host to the PC, from the PC to the host, from host to host, or PC to PC, usually without any special regard for the nature of the particular machines involved. Most implementations also allow files to be sent in groups, with a single command, such as "Send all my

Fortran files!" The scenario for each of these is always the same as above -- only the details of how to establish the actual connection dif- fer.

KERMIT works best with "printable" files -- files composed only of let-

ters, digits, punctuation marks, carriage returns, tabs, and so forth

-- since these can be represented on almost any kind of computer. KER-

MIT is also able to transfer "binary" files -- files such as executable programs -- composed of arbitrary bit patterns, but binary files nor- mally are meaningful only to the kind of computer on which they are

How to Use KERMIT Page 11 generated. Nevertheless, KERMIT can usually move such files from system

A to system B (where they are not much use) and back to system A in their original condition, although in some cases some special care must be taken to accomplish this.

Now that we have a basic understanding of what KERMIT does and how it works, let's look at some more concrete examples. First you need to know what the basic Kermit commands are.

2.4. Basic KERMIT Commands

These are generic descriptions of the most basic Kermit commands.

Detailed descriptions will come later. In these descriptions, local refers to the system that you are using directly, remote refers to the system to which you are CONNECTed via Kermit. Commands may take one or more operands on the same line, and are terminated by a carriage return.

SEND filespec Send the file or file group specified by filespec from

this Kermit to the other. The name of each file is

passed to the other Kermit in a special control packet,

so it can be stored there with the same name. A file

group is usually specified by including

"wildcard" characters like "*" in the file specifica-

tion. Examples:

send foo.txt

send *.for

Some implementations of Kermit may not support transfer

of file groups; these versions would require a separate

SEND command for each file to be transferred.

RECEIVE Receive a file or file group from the other Kermit. If

an incoming file name is not legal, then attempt to

transform it to a similar legal name, e.g. by deleting

illegal or excessive characters. The name thus formed

cannot be guaranteed to be unique, in which case

previously existing files could be overwritten. Some

versions of Kermit attempt to prevent this by warning

you of filename collisions and taking, or allowing for,

evasive action.

CONNECT Make a "virtual terminal" connection to the remote sys-

tem. On a PC or micro, this usually means to send all

keyboard input out the serial port, and display all in-

put from the serial port on the screen. To "escape"

from a virtual terminal connection, type Kermit's escape

character (e.g. CTRL-], control-rightbracket), followed

by the letter "C" for "Close Connection".

SET Establish various nonstandard settings, such as CONNECT

escape character, file characteristics, communication

line number, parity, or flow control.

How to Use KERMIT Page 12

SHOW Display the values of SET options.

HELP Type a summary of KERMIT commands and what they do.

EXIT Exit from KERMIT back to the host operating system.

? Typed anywhere within a KERMIT command: List the com-

mands, options, or operands that are possible at this

point. This command may or may not require a carriage

return, depending on the host operating system.

2.5. Real Examples

Kermit can be used in several ways: from a PC that is connected to a larger host computer; from a host computer which is connected to another host; from one PC to another.

2.5.1. PC to Host

In this example, the user is sitting at an IBM Personal Computer (PC), which is connected through its serial port to a DECSYSTEM-20 host com- puter. The IBM PC is local, the DEC-20 is remote. This example will also apply almost literally to any other microcomputer implementation of

Kermit.

You have started up your PC and have the Kermit program on your disk.

Begin by running Kermit on the PC. Use Kermit's CONNECT command to be- come a terminal to the DEC-20. In fact, the PC emulates the popular

Heath-19 (or VT52) terminal, so it is desirable to tell the DEC-20 that your terminal is one of these. Login on the DEC-20 and run Kermit there. Here is an example of this procedure with commands you type un- derlined:

5

A>kermit ! Run Kermit on the PC.

Kermit V1.20

Kermit-86> ! This is the Kermit prompt for the PC.

Kermit-86>connect ! Connect to the DEC-20.

[Connecting to host, type control-] to return to PC.

Baud rate is 9600, connecting over COM1.]

! You are now connected to the DEC-20.

CU20B ! The system prints its herald.

@terminal heath-19 ! Set your terminal type (optional).

@login my-id password ! Login using normal login method.

(At this point, the DEC-20 prints various messages.)

_______________

5

Everthing from a "!" mark to the end of line is commentary, not sys- tem typeout or part of a command.

How to Use KERMIT Page 13

@kermit ! Run Kermit on the DEC-20.

Kermit-20> ! This is Kermit-20's prompt.

You are now ready to transfer files between the two machines.

The following example illustrates how to send files from the DEC-20 to the PC. Note the use of the "*" wildcard character to denote a file group.

Kermit-20>send *.for ! Send all my FORTRAN files.

^]c ! Now return back to the PC by

! typing the escape sequence, in this case

! ^]C (Control-] followed by "C")

[Back at PC.]

Kermit-86>receive ! Tell the PC files are coming.

If you take more than about 5 seconds to get back to Kermit-86 and issue the RECEIVE command, the first packets from Kermit-20 may arrive prema- turely and appear on your screen, but no harm will be done because the packet will be retransmitted by the DEC-20 until the PC acknowledges it.

Once the connection is established, the PC will show you what is happen- ing -- it first clears the screen and waits for incoming packets; as packets arrive, the current file name and packet number will be con- tinuously displayed on the screen. When the PC's "Kermit-86>" prompt returns to your screen, the transfer is done. During file transfer, the microcomputer screen looks something like this:

IBM PC Kermit-86 V1.20

Number of Packets: 294 Receiving...

Number of Retries: 2

File Name: FOO.TXT

The packet and retry counts are continuously updated, and the word in the upper right tells the status of the transfer -- receiving, sending, complete, interrupted, or failed.

When the transfer is complete (most versions of KERMIT sound a beep to wake you up), you must CONNECT back to the DEC-20 host, EXIT from Kermit there, logout, and "escape back" to the PC as you did previously.

Kermit-86>connect ! Get back to the DEC-20.

[Connecting to host. Type CTRL-]C to return to PC.]

Kermit-20> ! Here we are.

Kermit-20>exit ! Get out of Kermit-20.

@logout ! Logout from the DEC-20.

Logged out Job 55, User MY-ID, Account MY-ACCOUNT, TTY 146,

at 24-Jan-84 15:18:56, Used 0:00:17 in 0:21:55

How to Use KERMIT Page 14

^]c ! Now "escape" back to the PC,

[Back at PC.]

Kermit-86>exit ! and exit from the PC's Kermit.

The files you transferred should now be on your PC disk.

To send files from the PC to the DEC-20, follow a similar procedure.

First follow the instructions in the previous section to log in to the

DEC-20 through the PC. Then in response to the host Kermit's

"Kermit-20>" prompt you type RECEIVE rather than SEND. Now escape back to the PC and use the SEND command to send the local PC files to DEC-20 host. The PC will show you the progress of the transmission on its screen.

When the "Kermit-86>" prompt indicates that the transmission is complete you should follow the procedure shown above to logout from the DEC-20 host, except that you may first wish to confirm that the files have been stored correctly in your directory on the DEC-20.

2.5.2. Host to Host

This section describes use of Kermit between two hosts. A "host" is considered to be a large or multi-user system, whose distinguishing characteristic is that it has multiple terminals. Use of Kermit for host-to-host file transfers differs from the PC-to-host case in that the line your terminal is connected to is not the same as the line over which the data is being transferred, and that some special commands may have to be issued to allow one Kermit to conform to unusual requirements of the other host.

In this example, you are already logged in to a DEC-20, and you use an

autodialer to connect to an IBM 370-series system running

VM/CMS through DEC-20 TTY port 12. The autodialer, in this example, is invoked from program called DIAL (idealized here, for simplicity), to which you merely supply the phone number.

@dial 765-4321/baud:1200

765-4321, baud 1200

[confirm]

Dialing your number, please hold...

Your party waiting is on TTY12:

@

Other methods exist for connecting two hosts with a serial line. Dedi- cated hookups can be made simply by running an EIA cable between TTY

6 ports on the two systems. For connecting to remote systems when no

_______________

6

Such a connection, by the way, usually requires the receive and transmit leads (pins 2 and 3) be swapped in one of the RS-232 connec- tors; this is called a "null modem" cable.

How to Use KERMIT Page 15 autodialer is available, a manual dialup connection is also possible,

7 but tricky. If you have a microcomputer that supports KERMIT, you may find it easier to first transfer from host A to the micro, then from the micro to host B.

The following procedure would be the same in any case, once a connection is made.

@

@kermit ! Run Kermit on the DEC-20.

Kermit-20>set ibm ! Turn on handshaking, parity, local echo.

Kermit-20>set line (to tty) 12 ! Indicate the line we'll use.

Kermit-20>connect ! And connect to it.

[KERMIT-20: Connecting over TTY12:, type <CTRL-Y>C to return.]

VM/370 ONLINE ! The IBM system prints its herald.

.login myuserid mypassword ! Login to IBM system.

LOGON AT 20:49:21 EST THURSDAY 01/20/84

CUVMB SP/CMS PUT 8210 01/19/84

.

.kermit

KERMIT-CMS>.send profile exec ! Send a file.

^Yc ! KERMIT-20's escape sequence typed here.

[KERMIT-20: Connection Closed. Back at DEC-20.]

Kermit-20>receive ! Tell Kermit-20 to RECEIVE.

The transfer takes place now; Kermit-20 will print the names of incoming files, followed by dots or percents to indicate the packet traffic (a dot for every 5 packets successfully transferred, a percent for every timeout or retransmission). It is complete when when you see "[OK]", a beep is sounded, and the Kermit-20 prompt next appears. At that point we connect back to the remote IBM system, exit from the remote Kermit and log out.

.

PROFILE.EXEC.1 ..%%.[OK]

Kermit-20>connect ! Get back to IBM and clean up.

[KERMIT-20: Connecting over TTY12:, type <CTRL-Y>C to return.]

_______________

7

Here's one way: log in on port x on your system, and assign another

port, y, to which you have physical access. Unplug the terminal from port y, and connect the terminal to a dialup modem. Dial up the remote computer and log in on it. Now, using a null modem cable, connect the modem directly to port y. Go back to your terminal on port x, run Kermit from it, and CONNECT to port y.

How to Use KERMIT Page 16

KERMIT-CMS>.

KERMIT-CMS>.exit

R;

.

SP/CMS

.logout

CONNECT= 00:03:01 VIRTCPU= 000:00.12 TOTCPU= 000:00.60

LOGOFF AT 20:52:24 EST THURSDAY 01/20/84

^Yc ! Type Kermit-20's escape sequence

[KERMIT-20: Connection Closed. Back at DEC-20.]

Kermit-20>exit ! All done with Kermit.

That's the whole procedure. The file is in your DEC-20 directory, com- pletely readable, as PROFILE.EXEC -- note that KERMIT-CMS translated from the IBM EBCDIC character encoding into standard ASCII, and con- verted the space between the file name and file type to a dot.

To send a file from the local host to the remote host, we would merely have reversed the SEND and RECEIVE commands in the example above.

2.5.3. Micro to Micro

Kermit also works between personal computers (microcomputers, workstations). The difference here is that commands are typed on two keyboards, rather than a single one. This is because a personal com- puter normally only accepts commands from its own keyboard. If one PC

Kermit CONNECTs to another, there will normally be no program on the other side to listen.

Making the physical connection between two micros is tricky. If the two

8 units are in close proximity , you can connect their serial ports with a null modem cable. However, different micros have different requirements

-- some may want a male connector on their serial port, others a female;

9 many require that certain of the RS-232 signals be held high or low .

In any case, you must also make sure the port speeds are the same at both ends.

_______________

8

Why would you want to run Kermit between two PCs that are next to each other? One good reason is that if they are different models, their floppy disks are probably incompatible.

9

By wiring certain of the pins in the connector together; for in- stance, some micros want DTR (Data Terminal Ready, pin 20) to be held high, and this might be accomplished by connecting it to CTS (Clear To

Send, pin 5). See EIA Standard RS-232-C, and the appropriate manuals for your micro.

How to Use KERMIT Page 17

Connections at longer distances can be made via dialup, providing the required modems are available (one side needs autoanswer capability), or using any kind of dedicated or switched circuit that may be available

-- PBX, port contention unit, almost anything you can plug an EIA con- nector into.

In this example, a DEC VT180 "Robin" CP/M microcomputer is connected to a Intertec "SuperBrain" CP/M micro, using a female-to-male null modem cable. Getting the cable right is the hard part. The connection can be tested by running Kermit and issuing the CONNECT command on both ends: typein from each micro should appear on the screen of the other.

Suppose you want to send a file FOO.HEX from the Robin to the Super-

Brain. Proceed as follows:

1. Run Kermit on the SuperBrain, and give the RECEIVE command:

A>kermit

Intertec SuperBrain Kermit-80 - V3.7

Kermit-80>receive

2. Run Kermit on the Robin, and give the SEND command for

FOO.HEX.

A>kermit

DEC VT18X Kermit-80 - V3.7

Kermit-80>send foo.hex

Watch the packets fly. When you get the next Kermit-80>

prompt, the transfer is done, and you can EXIT from both Ker-

mits.

The key point is to start the receiving end first -- most microcomputer

Kermits do not include a timeout facility, and if the receiver is not ready to receive when the sender first sends, there will be a protocol deadlock.

2.6. Another Way -- The KERMIT Server

So far, we have been describing the bare-bones version of the KERMIT protocol. An optional extension to the protocol includes the concept of a Kermit server. A KERMIT server is a Kermit program that does not in- teract directly with the user, but only with another Kermit program.

You do not type commands to a Kermit server, you merely start it at one end of the connection, and then type all further commands at the other end.

Not all implementations of Kermit can be servers, and not all know how to talk to servers -- but most of the major ones can and do. The server is run on the remote computer, which would normally be a large host,

such as the DEC-20. You must still connect to the remote host to log in and start the server, but you no longer have to tell one side to SEND and the other to RECEIVE, nor must you connect back to the remote side to clean up and log out when you're done. Using the server, you can do as many send and receive operations as you like without ever having to

How to Use KERMIT Page 18 connect back to the remote host. Some servers also provide additional services, such as directory listings, file deletion, or disk usage in- quiries.

A Kermit server is just a Kermit program running in a special mode. It acts much like ordinary Kermit does after you give it a RECEIVE command

-- it waits for a message from the other Kermit, but in this case the message is a command telling what to do, normally to send or to receive a file or group of files. After escaping back to the local system, you can give as many SEND and GET commands as you like, and when you're finished transferring files, you can give the BYE command, which sends a message to the remote Kermit server to log itself out. You don't have to connect back to the remote host and clean up. However, if you want to connect back to the host, you can use the FINISH command instead of

BYE, to shut down the Kermit server on the remote host without logging it off, allowing you to CONNECT back to your job there.

Here's an example of the use of a Kermit server. The user is sitting at a CP/M-80 microcomputer and a DEC-20 is the remote host.

A>kermit ! Run Kermit on the micro.

Kermit V3.9A

Kermit-80> ! This is the micro Kermit's prompt.

Kermit-80>connect ! Connect to the DEC-20.

[Connecting to remote host. Type CTRL-]C to return to micro.]

CU20E ! The DEC-20 prints its herald.

@login my-id password ! Log in normally.

(The DEC-20 prints various login messages here.)

@kermit ! Run Kermit-20 normally

Kermit-20>server ! Tell it to be a server.

Kermit Server running on DEC-20 host. Please type your escape

sequence to return to your local machine. Shut down the server by

typing the Kermit BYE command on your local machine.

^]c ! Now escape back to the micro.

[Connection closed, back at micro.]

Kermit-80>get *.pas ! Get all my DEC-20 Pascal programs.

Kermit-80>send foo.* ! Send all the "foo" files from my micro.

Kermit-80>exit ! Exit from Kermit back to CP/M.

A>

(Here you can do some work on the micro, edit files, whatever you like.)

A>kermit ! Run Kermit-80 some more.

Kermit-80>send file.pas ! Send another file.

Kermit-80>bye ! That's all. Shut down the Kermit server.

A> ! Back at CP/M automatically.

This is much simpler. Note that once you've started the Kermit Server on the remote end, you can run Kermit as often as you like on the micro without having to go back and forth any more; just make sure to shut the

How to Use KERMIT Page 19 server down when you're done by typing the BYE command.

Here are basic the commands available for talking to servers.

SEND filespec Sends a file or file group from the local host to the

remote host in the normal way.

GET filespec Ask the remote host to send a file or file group. Ex-

ample:

get *.c

This command is exactly equivalent to typing "send *.c"

at the remote host followed by "receive" on the local

host. Note that the local Kermit does not attempt to

validate the filespec. If the server cannot parse it,

or cannot access the specified file(s), it will send

back an appropriate error message.

BYE Shut down the remote server and exit from Kermit. This

will cause the job at the remote end to log itself out.

You need not connect back and clean up unless you get an

error message in response to this command (for instance,

if your logged-out disk quota is exceeded on the remote

host).

FINISH Shut down the server without having it log itself out,

and don't exit from Kermit. A subsequent CONNECT com-

mand will put you back at your job on the remote host,

at system command level.

When Things Go Wrong Page 20

3. When Things Go Wrong

Connecting two computers can be a tricky business, and many things can go wrong. Before you can transfer files at all, you must first estab- lish terminal communication. But successful terminal connection does not necessarily mean that file transfer will also work. And even when file transfer seems to be working, things can happen to ruin it.

3.1. Communication Line Problems

If you have a version of KERMIT on your microcomputer, but the CONNECT command doesn't seem to work at all, please:

- Make sure all the required physical connections have been made

and have not wiggled loose. If you are using a modem, make

sure the carrier light is on.

- If you have more than one connector on your micro, make sure

you are using the right one.

- Make sure that the port is set to the right communication

speed, or baud rate. Some versions of KERMIT have a built-

SET BAUD command, others require that you set the baud rate

using a system command or setup mode before you start the KER-

MIT program. Use the SHOW command to find out what the cur-

rent baud rate is.

- Make sure that the other communication line parameters, like

parity, bits per character, handshake, and flow control are

set correctly.

You must consult the appropriate manuals for the systems and equipment in question.

If all settings and connections appear to be correct, and communication still does not take place, the fault may be in your modem. Internal modems (i.e. those that plug in to a slot inside the microcomputer chassis) are not recommended for use with KERMIT. Many microcomputer

KERMIT programs are written to control the communication hardware ex- plicitly; internal modems can interfere with that control.

KERMIT normally expects to have full control of the communication port.

However, it is sometimes the case that some communications equipment controls the line between the two computers on either end. Examples in- clude modems (particularly "smart" modems), port contention or selection units, multiplexers, local networks, and wide-area networks. Such equi- pment can interfere with the KERMIT file transfer protocol in various ways:

- It can impose parity upon the communication line. This means

that the 8th bit of each character is used by the equipment to

check for correct transmission. Use of parity will:

* Cause packet checksums to appear incorrect to the

receiver and foil any attempt at file transfer. In most

When Things Go Wrong Page 21

cases, not even the first packet will get through.

* Prevent the use of the 8th bit for binary file data.

If terminal connection works but file transfer does not,

parity is the most likely culprit. To overcome this impedi-

ment, you should find out what parity is being used, and in-

form the KERMITs on each side (using the SET PARITY command)

so that they can:

* Compose and interpret the checksums correctly.

* Employ a special encoding to allow 8-bit data to pass

through the 7-bit communication channel.

Many packet-switched networks, such as GTE TELENET, require

10

parity to be set.

- Communications equipment can also interpret certain characters

in the data stream as commands rather than passing them along

to the other side. For instance, you might find your "smart"

modem suddenly disconnecting you and placing a call to Tas-

mania. The only way to work around such problems is to put

the device into "transparent" or "binary" mode. Most com-

munication devices have a way to do this; consult the ap-

propriate manual. In some cases, transparent mode will also

cancel the parity processing and allow the use of the 8th bit

for data.

3.2. The Transfer is Stuck

There are various ways in which Kermit file transfers can become stuck, but since many hosts are capable of generating timeout interrupts when input doesn't appear quickly enough, they can usually resend or "NAK"

(negatively acknowledge) lost packets. Nevertheless, if a transfer seems to be stuck, you can type RETURN on the keyboard of most micros to simulate a timeout.

An interesting exception is the IBM mainframe (VM/CMS) Kermit -- it can- not time out its "virtual console" (i.e. the user's terminal), so when using Kermit from a micro to an IBM host, occasional manual wakeups may be necessary.

The following sections discuss various reasons why a transfer in progress could become stuck. Before examining these, first make sure that you really have a Kermit on the other end of the line, and you have issued the appropriate command: SEND, RECEIVE, or SERVER. If the remote side is not a server, remember that you must connect back between each transfer and issue a new SEND or RECEIVE command.

_______________

10

TELENET uses MARK parity.

When Things Go Wrong Page 22

3.3. The Micro is Hung

The micro itself sometimes becomes hung for reasons beyond Kermit's con- trol, such as power fluctuations. If the micro's screen has not been updated for a long time, then the micro may be hung. Try these steps

(in the following order):

- Check the connection. Make sure no connectors have wiggled

loose from their sockets. If you're using a modem, make sure

you still have a carrier signal. Reestablish your connection

if you have to.

- Press RETURN to wake the micro up. This should clear up any

protocol deadlock. Several RETURNs might be necessary.

- If the problem was not a deadlock, restart the micro and then

restart Kermit, CONNECT back to the host, get back to your job

or login again, and restart the transfer. You may have to

stop and restart Kermit on the remote host.

3.4. The Remote Host Went Away

If your local system is working but the transfer is hung, maybe the remote host or the remote KERMIT program crashed. Get back to command level on the local KERMIT (on microcomputer implementations, you may be able to do this by typing about five RETURNs, or one or more

Control-C's). Issue the CONNECT command so that you can see what hap- pened. If the remote system has crashed then you will have to wait for it to come back, and restart whatever file that was being transferred at the time.

3.5. The Disk is Full

If your local floppy disk or remote directory fills up, the Kermit on the machine where this occurs will inform you and then terminate the transfer. You can continue the transfer by repeating the whole proce- dure either with a fresh floppy or after cleaning up your directory.

Some KERMIT programs allow you to continue the sequence where it left off, for instance on the DEC-20 by using the SEND command and including the name of the file that failed in the "(INITIAL)" field:

Kermit-20>send *.for (initial) foo.for

See the Kermit-20 command summary for further information about the in- itial filespec.

When Things Go Wrong Page 23

3.6. Message Interference

You may find that file transfers fail occasionally and upredictably.

One explanation could be that terminal messages are being mixed with your file packet data. These could include system broadcast messages

(like "System is going down in 30 minutes"), messages from other users

("Hi Fred, what's that KERMIT program you're always running?"), notifications that you have requested ("It's 7:30, go home!" or "You have mail from..."). Most KERMIT programs attempt to disable intrusive messages automatically, but not all can be guaranteed to do so. It may be necessary for you to "turn off" such messages before starting KERMIT.

3.7. Host Errors

Various error conditions can occur on the remote host that could effect file transmission. Whenever any such error occurs, the remote Kermit normally attempts to send an informative error message to the local one, and then breaks transmission, putting you back at Kermit command level on the local system.

3.8. File is Garbage

There are certain conditions under which Kermit can believe it trans- ferred a file correctly when in fact, it did not. The most likely cause has to do with the tricky business of file attributes, such as text vs binary, 7-bit vs 8-bit, blocked vs stream, and so forth. Each system has its own peculiarities, and each KERMIT has special commands to allow you to specify how a file should be sent or stored. However, these dif- ficulties usually crop up only when sending binary files. Textual files should normally present no problem between any two KERMIT programs.

3.9. Junk after End of File

When transferring a text file from a microcomputer to a mainframe, some- times you will find extraneous characters at the end of the file after it arrives on the target system. This is because many microcomputers don't have a consistent way of indicating the end of a file. CP/M is a good example. The minimum unit of storage on a CP/M floppy is a "block" of 128 bytes. Binary files always consist of a whole number of blocks, but a text file can end anywhere within a block. Since CP/M does not record a file's byte count, it uses the convention of marking the end with an imbedded Control-Z character. If your microcomputer version of

KERMIT is not looking for this character, it will send the entire last block, which may contain arbitrary junk after the "real" end of the file. To circumvent this problem, most microcomputer KERMITs have com- mands like SET FILE ASCII or SET FILE TEXT to instruct KERMIT to obey the CTRL-Z convention. Some microcomputer KERMITs operate in "text" mode by default, others in "binary" or "block" mode.

KERMIT Commands Page 24

4. KERMIT Commands

An "ideal" KERMIT program will be described here, which has most of the features specified in the KERMIT Protocol Manual. No KERMIT program will have all these commands or support all these options. The exact form of some of the commands may differ from version to version. Some

KERMIT programs may support system-dependent options not described here.

The intention of this description is to provide a base from which specific KERMIT programs can be described in terms of their differences from the "ideal."

4.1. Remote and Local Operation

Some KERMIT programs can be run in two ways, remote and local. A remote

Kermit is usually running on a mainframe, which you have CONNECTed to through a PC or other computer. When KERMIT runs remotely, all file transfer is done over the job's controlling terminal line -- the same line over which you logged in, and to which you would type interactive commands. What the system thinks is your terminal is really another computer, usually a microcomputer, running its own copy of Kermit.

When KERMIT is in "local mode", file transfer is done over an external device, such as a microcomputer's serial communication port, or an as- signed terminal line on a mainframe. The local Kermit is connected in some way (like a dialout mechanism) to another computer, again running its own copy of Kermit. A local Kermit is in control of the screen, a remote Kermit has no direct access to it. Microcomputer KERMITs usually run in local "mode", whereas mainframe Kermits usually need to be given some special command to run in local mode. Some commands make sense only for remote Kermits, others only for local, still others can be used with either. Local and remote operation of KERMIT is shown schemati- cally here:

PC is Local, Mainframe is Remote:

KERMIT Commands Page 25

Communication

Line (Packets)

+---------------/ /-----------------+ Other terminals

| | | | |

| | | | |

PC | LOCAL Mainframe | | | | REMOTE

+----------+----------+ +------------+--+--+--+--------+

| Serial Port | | | |

| | | | |

| | | | |

| +---------------+ | | Your job's |

| | Packets: 724 | | | terminal line |

| | Retries: 7 | | | |

| | File: FOO.BAR | | | |

| +---------------+ | | |

| Screen | | |

| | | |

+---------------+-----+ +------------------------------+

|

| (Commands)

|

+------------+---------+

\ Keyboard \

+----------------------+

You

The KERMIT program on the PC is a local Kermit. It can control the screen, the keyboard, and the port separately, thus it can update the screen with status information, watch for interrupt signals from the keyboard, and transfer packets on the communications port, all at the same time.

The KERMIT program running on the mainframe is a remote Kermit. The user logs in to the mainframe through a terminal port. The host com- puter cannot tell that the user is really coming in through a microcom- puter. The keyboard, screen, and port functions are all combined in user's mainframe terminal line. Therefore a remote Kermit is cut off from your screen and keyboard during file transfer.

A KERMIT server is always remote, and must get its commands from a local

KERMIT. The following descriptions will indicate when a command must be remote or local.

4.2. Command Interface

Most implementations (the UNIX version is the major exception) have an interactive keyword-style command interface, modeled after that of the

DECSYSTEM-20, which is roughly as follows: In response to the

"Kermit-xx>" prompt you may type a keyword, such as SEND, RECEIVE, or

EXIT, possibly followed by additional keywords or operands, each of which is called a field. You can abbreviate keywords (but not file names) to any length that makes them distinguishable from any other

KERMIT Commands Page 26 keyword valid for that field. You can type a question mark at any time to get information about what's expected or valid at that point. The

ESC and "?" features work best on full duplex systems (all but the IBM mainframe, so far), where the program can "wake up" immediately and per- form the required function. On half duplex or record-oriented systems, the ESC feature is not available, and the "?" requires a carriage return to follow.

In this example, the user types "set" and then a question mark to find out what the SET options are. The user then continues the command at the point where the question mark was typed, adding a "d" and another question mark to see what set options start with "d". The user then adds a "u" to select "duplex" (the only SET option that starts with

"du") followed by an ESC (shown here by a dollar sign) to complete the current field and issue the guide word "(to)" for the next one, then another question mark to see what the possibilities are, and so forth.

The command is finally terminated by a carriage return. Before carriage return is typed, however, the command can be edited using RUBOUT or other command editing keys. Finally, the same command is entered again with a minimum of keystrokes, with each field abbreviated to its shortest unique length. In the example, the parts the user types are underlined; all the rest is system typeout:

Kermit-20>set ? one of the following:

debugging delay duplex escape

file handshake IBM line

parity receive send

Kermit-20>set d? one of the following:

debugging delay duplex

Kermit-20>set du$plex (to) ? one of the following:

full half

Kermit-20>set duplex (to) h$alf

Kermit-20>set du h

4.3. Notation

In the command descriptions, the following notation is used: anything A parameter - the symbol in italics is replaced by an ar-

gument of the specified type (number, filename, etc).

[anything] An optional field. If omitted, it defaults to an ap-

propriate value. number A whole number, entered in prevailing notation of the sys-

tem. character A single character, entered literally, or as a number

(perhaps octal or hexadecimal) representing the ASCII value

of the character. floating-point-number

A "real" number, possibly containing a decimal point and a

fractional part.

KERMIT Commands Page 27 filespec A file specification, i.e. the name of a file, possibly in-

cluding a search path, device or directory name, or other

qualifying information, and possibly containing "wildcard"

or pattern-matching characters to denote a group of files.

^X A control character may be written using "uparrow" or

"caret" notation, since many systems display control charac-

ters this way. Control characters are produced by holding

down the key marked CTRL or Control and typing the ap-

propriate character, e.g. X.

Commands are shown in upper case, but can be entered in any combination of upper and lower case.

KERMIT Commands Page 28

4.4. Summary of KERMIT Commands

Here is a brief list of KERMIT commands as they are to be found in most

KERMIT programs. The following sections will describe these commands in detail.

For exchanging files:

SEND, RECEIVE, GET

For connecting to a remote host:

CONNECT, SET LINE, SET PARITY, SET DUPLEX, SET HANDSHAKE, SET ES-

CAPE, SET FLOW-CONTROL

For acting as a server:

SERVER

For talking to a server:

BYE, FINISH, GET, SEND, REMOTE

Setting nonstandard transmission and file parameters:

SET BLOCK-CHECK, SET DEBUG, SET DELAY, SET FILE, SET INCOMPLETE, SET

PARITY, SET RETRY;

SET SEND (or RECEIVE) END-OF-LINE, START-OF-PACKET, PACKET-LENGTH,

PAUSE, TIMEOUT, PADDING

For defining "macros" of SET commands:

DEFINE

For interrupting transmission:

Control-X, Control-Z, Control-C, Control-E

Getting information:

HELP, STATISTICS, SHOW

Executing command files:

TAKE

For recording the history of a file transfer operation:

LOG TRANSACTIONS

For non-protocol file capture or transmission:

LOG SESSION, TRANSMIT

For closing log files:

CLOSE

Leaving the program:

EXIT, QUIT

If you have a file called KERMIT.INI in your default or home disk, KER-

MIT will execute an automatic TAKE command on it upon initial startup.

KERMIT.INI may contain any KERMIT commands, for instance SET commands, or DEFINEs for SET macros to configure KERMIT to various systems or com- munications media. Note: Your particular implementation of KERMIT may use a different name for this file.

KERMIT Commands Page 29

4.5. The SEND Command

Syntax:

Sending a single file:

SEND nonwild-filespec1 [filespec2]

Sending multiple files:

SEND wild-filespec1 [filespec2]

The SEND command causes a file or file group to be sent to the other system. There are two forms of the command, depending on whether filespec1 contains "wildcard" characters. Use of wildcard characters is the most common method of indicating a group of files in a single file specification. For instance if FOO.FOR is a single file, a FORTRAN program named FOO, then *.FOR might be a group of FORTRAN programs.

Sending a File Group

If filespec1 contains wildcard characters then all matching files will be sent, in directory-listing order (according to the ASCII collating sequence) by name. If a file can't be opened for read access, it will be skipped. The initial file in a wildcard group can be specified with the optional filespec2. This allows a previously interrupted wildcard transfer to continue from where it left off, or it can be used to skip some files that would be transmitted first.

Sending a Single File

If filespec1 does not contain any wildcard characters, then the single file specified by filespec1 will be sent. Optionally, filespec2 may be used to specify the name under which the file will arrive at the target system; filespec2 is not parsed or validated locally in any way. If filespec2 is not specified, the file will be sent with its own name.

SEND Command General Operation

Files will be sent with their filename and filetype (for instance

FOO.BAR, no device or directory field, no generation number or attributes). If communication line parity is being used (see SET

PARITY), the sending KERMIT will request that the other KERMIT accept a special kind of prefix notation for binary files. This is an advanced feature, and not all KERMITs have it; if the other KERMIT does not agree to use this feature, binary files cannot be sent correctly.

The sending KERMIT will also ask the other KERMIT whether it can handle

a special prefix encoding for repeated characters. If it can, then files with long strings of repeated characters will be transmitted very efficiently. Columnar data, highly indented text, and binary files are the major beneficiaries of this technique.

KERMIT Commands Page 30

SEND Remote Operation

If you are running KERMIT remotely (for instance, from a microcomputer), you should "escape back" to your local Kermit within a reasonable amount of time and give the RECEIVE command. Don't take more than a minute or two to complete the switch, or KERMIT may "time out" and give up (in that case, you'll have to CONNECT back to the remote system and reissue the SEND command).

SEND Local Operation

If you're running KERMIT locally, for instance on a microcomputer, you should have already run KERMIT on the remote system and issued either a

RECEIVE or a SERVER command.

Once you give KERMIT the SEND command, the name of each file will be printed on your screen as the transfer begins, and information will be displayed to indicate the packet traffic. When the specified operation is complete, the program will sound a beep, and the status of the opera- tion will be indicated by a message like OK, Complete, Interrupted, or

Failed.

If you see many packet retry indications, you are probably suffering from a noisy connection. You may be able to cut down on the retransmis- sions by using SET SEND PACKET-LENGTH to decrease the packet length; this will reduce the probability that a given packet will be corrupted by noise, and reduce the time required to retransmit a corrupted packet.

If you notice a file being sent which you do not really want to send, you may cancel the operation immediately by typing either Control-X or

Control-Z. If your are sending a file group, Control-X will cause the current file to be skipped, and KERMIT will go on to the next file, whereas Control-Z will cancel sending the entire group and return you to

KERMIT-20 command level.

4.6. The RECEIVE Command

Syntax: RECEIVE [filespec]

The RECEIVE command tells KERMIT to wait for the arrival a file or file group sent by a SEND command from the other system. If only one file is being received, you may include the optional filespec as the name to store the incoming file under; otherwise, the name is taken from the in- coming file header. If the name in the header is not a legal file name on the local system, KERMIT will attempt to transform it to a legal name.

If an incoming file has the same name as an existing file, KERMIT will either overwrite the old file or else try to create a new unique name,

depending on the setting of FILE WARNING.

If you have SET PARITY, then 8th-bit prefixing will be requested. If the other side cannot do this, binary files cannot be transferred cor- rectly. The sending KERMIT may also request that repeated characters be

KERMIT Commands Page 31 compressed.

If an incoming file does not arrive in its entirety, KERMIT will nor- mally discard it; it will not appear in your directory. You may change this behavior by using the command SET INCOMPLETE KEEP, which will cause as much of the file as arrived to be saved in your directory.

RECEIVE Remote Operation

If your are running KERMIT remotely, you should escape back to your local Kermit and give the SEND command. You should do this within about two minutes, or KERMIT may time out and give up; if this happens, you can CONNECT back to the remote system and reissue the RECEIVE command.

RECEIVE Local Operation

If you are running KERMIT locally, you should already have issued a SEND

11 command to the remote KERMIT, and then escaped back to DEC-20 Kermit.

As files arrive, their names will be shown on your screen, along with a continuous display the packet traffic.

If a file begins to arrives that you don't really want, you can attempt to cancel it by typing Control-X; this sends a cancellation request to the remote Kermit. If the remote Kermit understands this request (not all implementations of Kermit support this feature), it will comply; otherwise it will continue to send. If a file group is being sent, you can request the entire group be cancelled by typing Control-Z.

4.7. GET

LOCAL ONLY -- Syntax: GET [remote-filespec]

The GET command requests a remote KERMIT server to send the file or file group specified by remote-filespec. Note the distinction between the

RECEIVE and GET commands: RECEIVE puts KERMIT into a passive wait state, whereas GET actively sends a command to a server.

The GET command can be used only when KERMIT is local, with a KERMIT server on the other end of the line. This means that you must have CON-

NECTed to the other system, logged in, run KERMIT there, issued the

SERVER command, and escaped back to the local KERMIT.

The remote filespec is any string that can be a legal file specification for the remote system; it is not parsed or validated locally. As files arrive, their names will be displayed on your screen, along with a con-

_______________

11

not SERVER -- use the GET command to receive files from a KERMIT server.

KERMIT Commands Page 32 tinuous indication of the packet traffic. As in the RECEIVE command, you may type Control-X to request that the current incoming file be can- celled, Control-Z to request that the entire incoming batch be can- celled.

If the remote KERMIT is not capable of server functions, then you will probably get an error message back from it like "Illegal packet type".

In this case, you must connect to the other Kermit, give a SEND command, escape back, and give a RECEIVE command.

Optional Syntax: If you are requesting a single file, you may type the

GET command without a filespec. In that case, Kermit programs that implement the optional GET syntax will prompt you for the remote filespec on the subsequent line, and the name to store it under when it arrives on the line after that:

Kermit-MS>get

Remote Source File: aux.txt

Local Destination File: auxfile.txt

4.8. SERVER

REMOTE ONLY -- Syntax: SERVER

The SERVER command instructs KERMIT to cease taking commands from the keyboard and to receive all further instructions in the form of KERMIT packets from another system. A KERMIT server must be remote; that is, you must be logged in to the system through another computer, such as a microcomputer. In addition, your local KERMIT should have commands for communicating with remote servers; these include GET, FINISH, and BYE.

After issuing this command, escape back to your local system and issue

SEND, GET, BYE, FINISH, or other server-oriented commands from there.

If your local KERMIT does not have a BYE command, then it does not have the full ability to communicate with a KERMIT server and you should not put the remote KERMIT into SERVER mode. If your local KERMIT does have a BYE command, use it to shut down and log out the KERMIT server when you are done with it.

Any nonstandard parameters should be selected with SET commands before putting KERMIT in server mode, in particular the block check type and special file modes.

4.9. BYE

LOCAL ONLY -- Syntax: BYE

When running as a local Kermit talking to a KERMIT server, use the BYE command to shut down and log out the server. This will also close any

debugging log files and exit from the local KERMIT.

KERMIT Commands Page 33

4.10. FINISH

LOCAL ONLY -- Syntax: FINISH

When running as a local Kermit talking to a remote KERMIT server use the

FINISH command to shut down the server without logging out the remote job, so that you can CONNECT back to it. Also, close any local debug- ging log file.

4.11. REMOTE

LOCAL ONLY -- Syntax: REMOTE command

When running in local mode, talking to a remote KERMIT server send the specified command to the remote server. If the server does not under- stand the command (all of these commands are optional features of the

KERMIT protocol), it will reply with a message like "Unknown KERMIT server command". If does understand, it will send the results back, and they will be displayed on the screen. The REMOTE commands are:

CWD [directory] Change Working Directory. If no directory name is

provided, the server will change to the default direc-

tory. Otherwise, you will be prompted for a password,

and the server will attempt to change to the specified

directory. If access is not granted, the server will

provide a message to that effect.

DELETE filespec Delete the specified file or files. The names of the

files that are deleted will appear on your screen.

DIRECTORY [filespec]

The names of the files that match the given file

specification will be displayed on your screen. If no

file specification is given, all files from the current

directory will be listed.

DISK [directory]

Provide information about disk usage in the current

directory, such as the quota, the current storage, the

amount of remaining free space.

HELP Provide a list of the functions that are available.

HOST [command] Pass the given command to the server's host command

processor, and display the resulting output on your

screen.

KERMIT [command]

Pass the given command, which is expressed in the server

KERMIT's own interactive-mode command syntax, to the

server for execution. This is useful for changing set-

tings, logging, and other functions.

RUN program-name [command-line-argument]

Have the remote KERMIT run the indicated program with

KERMIT Commands Page 34

the indicated command line; send the results back to

your screen.

PROGRAM [command]

Send the command to the program started by most recent

REMOTE RUN program, and display the results on the

screen. If no command is given, send newline character.

TYPE filespec Display the contents of the specified file on your

screen.

4.12. LOCAL

Syntax: LOCAL command

Execute the specified command on the local system -- on the system where

KERMIT to which your are typing this command is running. These commands provide some local file management capability without having to leave the KERMIT program, which is particularly useful on microcomputers.

CWD [directory] "Change Working Directory" to the specified directory.

DELETE filespec Delete the specified file or files.

DIRECTORY [filespec] Provide a directory listing of the specified files.

Some KERMIT programs may provide commands for these or other functions in the syntax of their own system, when this would cause no confusion.

For instance, CP/M KERMIT may use ERA in place of LOCAL DELETE.

4.13. CONNECT

LOCAL ONLY -- Syntax: CONNECT [terminal-designator]

Establish a terminal connection to the system at the other end of the communication line. On a microcomputer, this is normally the serial port. On a mainframe, you will have to specify a terminal line number or other identifier, either in the CONNECT command itself, or in a SET

LINE command. Get back to the local KERMIT by typing the escape charac- ter followed by a single character "command". Several single-character commands are possible:

C Close the connection and return to the local KERMIT.

S Show status of the connection.

B Send a BREAK signal.

0 (zero) Send a NUL (0) character.

P Push to the local system command processor without breaking the

connection.

Q Quit logging session transcript.

R Resume logging session transcript.

? List all the possible single-character arguments.

^] (or whatever you have set the escape character to be)

Typing the escape character twice sends one copy of it to the con-

nected host.

KERMIT Commands Page 35

You can use the SET ESCAPE command to define a different escape charac- ter, and SET PARITY, SET DUPLEX, SET FLOW-CONTROL, SET HANDSHAKE to es- tablish or change those parameters.

4.14. HELP

Syntax: HELP

Typing HELP alone prints a brief summary of KERMIT and its commands, and possibly instructions for obtaining more detailed help on particular topics. Most KERMIT implementations also allow the use of "?" within a command to produce a short help message.

4.15. TAKE

TAKE filespec

Execute KERMIT commands from the specified file. The file may contain contain any valid KERMIT commands, including other TAKE commands.

4.16. EXIT, QUIT

EXIT

Exit from KERMIT.

QUIT is a synonym for EXIT.

4.17. The SET Command

Syntax: SET parameter [option] [value]

Establish or modify various parameters for file transfer or terminal connection.

When a file transfer operation begins, the two KERMITs automatically ex- change special initialization messages, in which each program provides the other with certain information about itself. This information in- cludes the maximum packet size it wants to receive, the timeout interval it wants the other KERMIT to use, the number and type of padding charac- ters it needs, the end-of-line character it needs to terminate each packet (if any), the block check type, the desired prefixes for control characters, characters with the "high bit" set, and repeated characters.

Each KERMIT program has its own preset "default" values for these parameters, and you normally need not concern yourself with them. You can examine their values with the SHOW command; the SET command is provided to allow you to change them in order to adapt to unusual con-

ditions.

The following parameters may be SET:

BAUD-RATE Set the speed of the current communications port

KERMIT Commands Page 36

BLOCK-CHECK Packet transmission error detection method

DEBUGGING Mode or log file

DELAY How long to wait before starting to send

DUPLEX For terminal connection, full (remote echo) or half

(local echo)

ESCAPE Character for terminal connection

FILE For setting file parameters like name conversion and

byte size

FLOW-CONTROL Selecting flow control method, like XON/XOFF

HANDSHAKE For turning around half duplex communication line

IBM Set things up for communicating with an IBM mainframe

INCOMPLETE What to do with an incomplete file

LINE Terminal line to use for terminal connection or file

transfer

PARITY Character parity to use

PORT For switching communication ports

PROMPT For changing the program's command prompt

RECEIVE Various parameters for receiving files

RETRY How many times to retry a packet before giving up

SEND Various parameters for sending files

The DEFINE command may be used to compose "macros" by combining SET com- mands. The SET commands are now described in detail.

SET BAUD-RATE

Set or change the baud rate (approximate translation: transmission speed in bits per second) on the currently selected communications device.

The way of specifying the baud rate varies from system to system; in most cases, the actual number (such as 1200 or 9600) is typed. Systems that do not provide this command generally expect that the speed of the line has already been set appropriately outside of KERMIT.

SET BLOCK-CHECK

KERMIT normally uses a 1-character block check, or "checksum", on each packet. The sender of the packet computes the block check based on the other characters in the packet, and the receiver recomputes it the same way. If these quantities agree, the packet is accepted and the trans- mission proceeds. If they disagree, the packet is rejected and trans- mitted again.

However, the block check is not a foolproof method of error detection.

The normal single-character KERMIT block check is only a 6-bit quantity

(the low order 8 bits of the arithmetic sum folded upon itself). With

6 only six bits of accuracy, the chances are one in 2 -- that is, 1/64

-- that an error can occur which will not be detected in the checksum, assuming that all errors are equally likely.

You can decrease the probability that an error can slip through, at the expense of transmission efficiency, by using the SET BLOCK-CHECK command to select more rigorous block check methods. Note that all three methods will detect any single-bit error, or any error in an odd number

KERMIT Commands Page 37 of bits. The options are:

1-CHARACTER-CHECKSUM:

The normal single-character 6-bit checksum.

2-CHARACTER-CHECKSUM:

A 2-character, 12-bit checksum. Reduces the probability

of an error going undetected to 1/4096, but adds an ex-

tra character to each packet.

3-CHARACTER-CRC:

A 3-character, 16-bit Cyclic Redundancy Check, CCITT

format. In addition to errors in any odd number of

bits, this method detects double bit errors, all error

bursts of length 16 or less, and more than 99.99% of all

possible longer bursts. Adds two extra characters to

each packet.

The single character checksum has proven to be quite adequate in prac- tice, much more effective than straightforward analysis would indicate, since all errors are not equally likely, and a simple checksum is well suited to catching the kinds of errors that are typical of telecom- munication lines. The other methods should be requested only when the connection is very noisy.

Note that the 2- and 3-character block checks are not available in all versions of KERMIT; if the other KERMIT is not capable of performing the higher-precision block checks, the transfer will automatically use the standard single-character method.

SET DEBUG

Syntax: SET DEBUG options

Record the packet traffic, either on your terminal or in a file. Op- tions are:

STATES Show Kermit state transitions and packet numbers

(brief).

PACKETS Display each incoming and outgoing packet (lengthy).

LOG-FILE Log the selected information (STATES or PACKETS) to the

specified file. If log file not specified, then use the

terminal if local.

OFF Don't display debugging information (this is the

default). If debugging was in effect, turn it off and

close any log file.

KERMIT Commands Page 38

SET DELAY

Syntax: SET DELAY number

Specify how many seconds to wait before sending the first packet after a

SEND command. Use when remote and SENDing files back to your local Ker- mit. This gives you time to "escape" back and issue a RECEIVE command.

The normal delay is 5 seconds. In local mode or server mode, KERMIT does not delay before sending the first packet.

SET DUPLEX

Syntax: SET DUPLEX keyword

For use when CONNECTed to a remote system. The keyword choices are FULL and HALF. FULL means the remote system echoes the characters you type,

HALF means the local system echoes them. FULL is the default, and is used by most hosts. HALF is necessary when connecting to IBM mainframes. Half duplex is also called "local echo".

SET ESCAPE

Syntax: SET ESCAPE character

Specify or change the character you want to use to "escape" from remote connections back to KERMIT. This would normally be a character you don't expect to be using on the remote system, perhaps a control charac- ter like ^\, ^], ^^, or ^_. Most versions of KERMIT use one of these by default. After you type the escape character, you must follow it by a single-character "argument", such as "C" for Close Connection. The ar- guments are listed above, under the description of the CONNECT command.

SET FILE

Syntax: SET FILE parameter keyword

Establish file-related parameters. Depending on the characteristics of the system, it may be necessary to tell KERMIT how to fetch an outbound file from the disk, or how to store an incoming file. The actual parameters you can specify in this command will vary from system to sys- tem, and you should consult the documentation for your particular ver- sion of KERMIT. Some examples would be byte size (PDP-10 architecture), record length or block size (record oriented systems), end-of-file detection method (on microcomputers).

This can be a very important command if you intend to transfer binary files, but is normally unecessary for transmitting textual files.

KERMIT Commands Page 39

SET FLOW-CONTROL

Syntax: SET FLOW-CONTROL option

For communicating with full duplex systems. System-level flow control is not necessary to the KERMIT protocol, but it can help to use it if the same method is available on both systems. The most common type of flow control on full duplex systems is XON/XOFF.

SET HANDSHAKE

Syntax: SET HANDSHAKE option

For communicating with half duplex systems. This lets you specify the line turnaround character sent by the half duplex host to indicate it has ended its transmission and is granting you permission to transmit.

When a handshake is set, KERMIT will not send a packet until the half duplex host has sent the specified character (or a timeout has occurred). The options may include:

NONE No handshake; undo the effect of any previous SET HANDSHAKE.

XOFF Control-S.

XON Control-Q.

BELL Control-G.

CR Carriage Return, Control-M.

LF Linefeed, Control-J.

ESC Escape, Control-[.

SET INCOMPLETE

Syntax: SET INCOMPLETE option

Specify what to do when a file transfer fails before it is completed.

The options are DISCARD (the default) and KEEP. If you choose KEEP, then if a transfer fails to complete successfully, you will be able to keep the incomplete part that was received.

SET LINE

Syntax: SET LINE [terminal-designator]

Specify the terminal line to use for file transfer or CONNECT. This command is found on mainframe KERMITs, which normally run in "remote mode" using their own controlling terminal for file transfer. Specify- ing a separate line puts the program in "local mode." If no line is specified, revert to the job's controlling terminal, i.e. go back to

"remote mode."

KERMIT Commands Page 40

SET PORT

Syntax: SET PORT terminal-designator

Specify the communications port for file transfer or CONNECT. This com- mand is found on microcomputer KERMITs that run in "local" mode. SET

PORT does not change the remote/local status but simply selects a dif- ferent port for local operation.

SET PARITY

Syntax: SET PARITY keyword

Parity is a technique used by communications equipment for detecting er- rors on a per-character basis; the "8th bit" of each character acts as a check bit for the other seven bits. KERMIT uses block checks to detect errors on a per-packet basis, and it does not use character parity.

However, some systems that KERMIT runs on, or equipment through which these systems communicate, may be using character parity. If KERMIT does not know about this, arriving data will have been modified and the block check will appear to be wrong, and packets will be rejected.

If parity is being used on the communication line, you must inform both

KERMITs, so the desired parity can be added to outgoing characters, and stripped from incoming ones. SET PARITY should be used for communicat- ing with hosts that require character parity (IBM mainframes are typical examples) or through devices or networks (like GTE TELENET) that add parity to characters that pass through them. Both KERMITs should be set to the same parity. The specified parity is used both for terminal con- nection (CONNECT) and file transfer (SEND, RECEIVE, GET).

The choices for SET PARITY are:

NONE (the default) eight data bits and no parity bit.

MARK seven data bits with the parity bit set to one.

SPACE seven data bits with the parity bit set to zero.

EVEN seven data bits with the parity bit set to make the overall

parity even.

ODD seven data bits with the parity bit set to make the overall

parity odd.

NONE means no parity processing is done, and the 8th bit of each charac- ter can be used for data when transmitting binary files.

If you have set parity to ODD, EVEN, MARK, or SPACE, then advanced ver- sions of KERMIT will request that binary files will be transferred using

8th-bit-prefixing. If the KERMIT on the other side knows how to do

8th-bit-prefixing (this is an optional feature of the KERMIT protocol, and not all implementations of KERMIT have it), then binary files can be transmitted successfully. If NONE is specified, 8th-bit-prefixing will

not be requested.

KERMIT Commands Page 41

SET PROMPT

This allows you to change the program's prompt. This is particularly useful if you are using KERMIT to transfer files between two systems of the same kind, in which case you can change the prompts of the KERMIT programs involved to include appropriate distinguishing information.

SET SEND

SET SEND parameter

Parameters for outgoing packets, as follows:

END-OF-LINE character

The ASCII character to be used as a line terminator for packets,

if one is required by the other system, carriage return by

default. You will only have to use this command for systems

that require a line terminator other than carriage return.

PACKET-LENGTH number

Maximum packet length to send between 10 and 94 (decimal).

Shortening the packets might allow more of them to get through

through without error on noisy communication lines. Lengthening

the packets increases the throughput on clean lines.

TIMEOUT number

How many seconds to wait for a packet before trying again.

PAUSE floating-point-number

How many seconds to pause before sending each data packet. Set-

ting this to a nonzero value may allow some slow systems enough

time to consolidate itself packet before the next packet ar-

rives. Normally, no per-packet pausing is done.

PADDING number, PADCHAR character

How much padding to send before a packet, if the other side

needs padding, and what character to use for padding. Defaults

are no padding, and NUL (0) for the padding character.

QUOTE character

What printable character to use for quoting of control charac-

ters, "#" (43) by default. There should be no reason to change

this.

START-OF-PACKET character

The start-of-packet character is the only control character used

"bare" by the KERMIT protocol. It is Control-A by default. If

a bare Control-A causes problems for your communication hardware

or software, you can use this command to select a different con-

trol character to mark the start of a packet. You must also

issue the reciprocal command (SET RECEIVE START-OF-PACKET) to

the KERMIT on the other system (providing it has such a

command).

KERMIT Commands Page 42

SET RECEIVE

Syntax: SET RECEIVE parameter

Parameters to request or expect for incoming packets, as follows:

END-OF-LINE character

Carriage return (15) by default.

PACKET-LENGTH number

Maximum length packet for the other side to send, decimal num-

ber, between 10 and 94, decimal.

TIMEOUT number

How many seconds the other Kermit should wait for a packet be-

fore asking for retransmission.

PAUSE floating-point-number

How many seconds to pause before acknowledging a packet. Set-

ting this to a nonzero value will slow down the rate at which

data packets arrive, which may be necessary for systems that

have "sensitive" front ends and cannot accept input at a high

rate.

PADDING number, PADCHAR character

How many padding characters to request before each incoming

packet, and what the padding character should be. No KERMITs

are known to need padding, and if one did, it would request it

without your having to tell it to do so. This command would

only be necessary, therefore, under very unusual circumstances.

QUOTE character

What printable character to use for quoting of control charac-

ters, "#" (43) by default. There should be no reason to change

this.

START-OF-PACKET character

The control character to mark the beginning of incoming packets.

Normally SOH (Control-A, ASCII 1) (see SET SEND START-OF-PACKET,

above).

SET RETRY

SET RETRY option number

Set the maximum number of retries allowed for:

INITIAL-CONNECTION

How many times to try connecting before giving up, normally

something like 15.

PACKETS How many times to try sending a particular packet before giving

up, normally 5. If a line is very noisy, you might want to in-

crease this number.

KERMIT Commands Page 43

4.18. DEFINE

DEFINE macroname [set-parameters]

Define a "SET macro" to allow convenient association of one or more SET parameters with a mnemonic keyword of your choice. The SET parameters are a list of one or more SET options, separated by commas. If you use

KERMIT to communicate with several different kinds of systems, you may set up a macro for each, for instance:

DEFINE IBM PARITY MARK, DUPLEX HALF, HANDSHAKE XON

DEFINE UNIX PARITY NONE, DUPLEX FULL, HANDSHAKE NONE

DEFINE TELENET PARITY MARK, RECEIVE TIMEOUT 20

You may then type SET IBM, SET UNIX, and so forth to set all the desired parameters with a single command. It is convenient to include these definitions in your KERMIT.INI file.

Another other handy use for SET macros would be for rapid adaptation to different conditions of line noise:

DEFINE CLEAN BLOCK-CHECK 1, SEND PACKET-LENGTH 94, RETRY PACKET 5

DEFINE NOISY BLOCK-CHECK 2, SEND PACKET-LENGTH 60, RETRY PACKET 10

DEFINE VERY-NOISY BLOCK 3, SEND PACKET 40, RETRY PACKET 20

You may redefine an existing macro in the same manner as you defined it.

You can undefine an existing macro by typing an empty DEFINE command for it, for instance:

DEFINE IBM

You can list all your macros and their definitions with the SHOW MACROS command.

4.19. SHOW

Syntax: SHOW [option]

The SHOW command displays the values of the parameters settable by the

SET command. If a particular option is not requested, a complete dis- play will be provided.

4.20. STATISTICS

Give statistics about the most recent file transfer, such as the total number of characters transmitted, the effective baud rate, and so forth.

KERMIT Commands Page 44

4.21. LOG

Syntax: LOG [option] [filespec]

Log the specified entity to the specified log file.

TRANSACTIONS Direct KERMIT to log transactions, such as files suc-

cessfully sent or received or files that could not be

successfully sent or received. A transaction is useful

recording the progress of a long, unattended multifile

transfer.

SESSION Create a transcript of a CONNECT session, when running a

local KERMIT connected to a remote system, in the

specified file. The log is closed when connection is

closed. In some implementations, logging can be

"toggled" by typing the connect escape character fol-

lowed by Q (Quit logging) or R (Resume logging) or

similar single-character commands. Session-logging is

useful for recording dialog with an interactive system,

and for "capturing" from systems that don't have KERMIT.

No guarantee can be made that the file will arrive cor-

rectly or completely, since no error checking takes

place.

DEBUGGING Record debugging information in the specified file.

There may be several options to select the desired in-

formation -- entire packets, state transitions, etc

-- available via the SET DEBUGGING command.

4.22. TRANSMIT

Syntax: TRANSMIT filespec

Send the contents of the specified file to the other system "bare", without protocol, packets, error checking, or retransmission. This com- mand is useful for sending standard logon or connection sequences, and for sending files to systems that don't have KERMIT. No guarantee can be made that the target system will receive the file correctly and com- pletely. When receiving a file, the target system would normally be running a text editor in text collection mode.

KERMIT Implementations Page 45

5. KERMIT Implementations

Kermit has been written for a wide variety of systems, both mainframes and microcomputers. Kermit is not written in a portable language; rather, each implemenation is written in the language best suited for the particular machine. The specification, given in the Kermit Protocol

Manual, is quite general and allows implementation on almost any machine.

Here's a brief table summarizing the known Kermit implementations, as of this writing. This list is constantly growing, and may be far out of date by the time you read it.

Machine Operating System Language

DECsystem-10,20 TOPS-10,20 MACRO-10,20

IBM 370 Series VM/CMS, MVS/TSO IBM Assembler

IBM 370 Series MTS Pascal

CDC Cyber 170 NOS Fortran-77

Sperry/Univac-1100 EXEC EXEC Assembler

Honeywell MULTICS PL/I

DEC VAX-11 VMS Bliss-32, Macro-32

DEC PDP-11 RT,RSX,RSTS,MUMPS MACRO-11 & others

DEC Pro-300 Series P/OS Bliss-16, Macro-11

VAX,PDP-11,SUN,etc UNIX C

PRIME PRIMOS PL/P

HP3000, Univac, etc Software Tools Ratfor

HP1000 RTE Fortran

Apollo Aegis Fortran

Terak, HP-98x6, IBM PC UCSD p-System

8080, 8085, or Z80 CP/M-80 ASM

8086, 8088 PC-DOS, MS-DOS MS MASM-86

8086, 8088 CP/M-86 DR ASM86

Apple II 6502 Apple DOS DEC-10/20 CROSS

TRS80 I, III TRSDOS Z80 Assembler

Atari DOS Action!

The 8080 version runs on the DEC VT180, DECmate II (CP/M), Heath/

Zenith-89 and 100, Superbrain, Apple II/Z80, TRS-80 II (CP/M), Osborne,

Kaypro, and others. There are 8086 MS DOS versions for the IBM PC, DEC

Rainbow, Wang PC, Compaq, Heath/Zenith-100, HP-150, Tandy 2000, Victor

9000, and others. The 8086 CP/M-86 version runs on the DEC Rainbow and the NEC APC.

The remainder of the KERMIT User Guide is devoted to descriptions of selected KERMIT implementations. If a description of your version of

KERMIT does not appear, look in the KERMIT area on your mainframe for an on-line documentation file. Even if your version is described below, the version of the manual you are reading may be out of date and the on- line information may be more current.

DECSYSTEM-20 KERMIT Page 46

6. DECSYSTEM-20 KERMIT

Authors: Frank da Cruz, Bill Catchings, Columbia University

Language: MACRO-20

Version: 4.1(236)

Date: July 3, 1984

KERMIT-20 Capabilities At A Glance:

Local operation: Yes

Remote operation: Yes

Transfers text files: Yes

Transfers binary files: Yes

Wildcard send: Yes

^X/^Y interruption: Yes

Filename collision avoidance: (Uses generation numbers)

Can time out: Yes

8th-bit prefixing: Yes

Repeat count prefixing: Yes

Alternate block checks: Yes

Terminal emulation: Yes

Communication settings: Yes

Transmit BREAK: Yes

IBM communication: Yes

Transaction logging: Yes

Session logging: Yes

Raw transmit: No

Act as server: Yes

Talk to server: Yes

Advanced commands for servers: Yes

Local file management: Yes

Handle file attributes: No

Command/init files: Yes

KERMIT-20 is a program that implements the KERMIT file transfer protocol for the Digital Equipment Corporation DECSYSTEM-20 mainframe computer.

It is written in MACRO-20 assembly language and should run on any DEC-20 system with version 4 of TOPS-20 or later.

The KERMIT-20 section will describe the things you should know about the

DEC-20 file system in order to make effective use of KERMIT, and then it will describe the special features of the KERMIT-20 program.

6.1. The DEC-20 File System

The features of the DEC-20 file system of greatest interest to KERMIT users are the form of the file specifications, and the distinctions be- tween text and binary files.

DECSYSTEM-20 KERMIT Page 47

DEC-20 File Specifications

DEC-20 file specifications are of the form

DEVICE:<DIRECTORY>NAME.TYPE.GEN;ATTRIBUTES where the DIRECTORY, NAME, and TYPE may each be up to 39 characters in length, GEN is a generation (version number), and various attributes are possible (protection code, account, temporary, etc). Generation and at- tributes are normally omitted. Device and directory, when omitted, default to the user's own (or "connected") disk and directory. Thus

NAME.TYPE is normally sufficient to specify a file, and only this infor- mation is sent along by KERMIT-20 with an outgoing file.

The device, directory, name, and type fields may contain uppercase let- ters, digits, and the special characters "-" (dash), "_" (underscore), and "$" (dollar sign). There are no imbedded or trailing spaces. Other characters may be included by prefixing them (each) with a Control-V.

The fields of the file specification are set off from one another by the punctuation indicated above.

The device field specifies a physical or "logical" device upon which the file is resident. The directory field indicates the area on the device, for instance the area belonging to the owner of the file. KERMIT-20 does not transmit the device or directory fields to the target system, and does not attempt to honor device or directory fields that may appear in incoming file names; for instance, it will not create new direc- tories.

The name is the primary identifier for the file. The type, also called the "extension", is an indicator which, by convention, tells what kind of file we have. For instance FOO.FOR is the source of a Fortran program named FOO; FOO.REL might be the relocatable object module produced by compiling FOO.FOR; FOO.EXE could an executable program produced by LOADing and SAVing FOO.REL, and so forth.

The DEC-20 allows a group of files to be specified in a single file specification by including the special "wildcard" characters, "*" and

"%". A "*" matches any string of characters, including no characters at all; a "%" matches any single character. Here are some examples:

*.FOR All files of type FOR (all Fortran source files) in the con-

nected directory.

FOO.* Files of all types with name FOO.

F*.* All files whose names start with F.

F*X*.* All files whose names start with F and contain at least one X.

%.* All files whose names are exactly one character long.

*.%%%* All files whose types are at least three characters long.

Wildcard notation is used on many computer systems in similar ways, and it is the mechanism most commonly used to instruct KERMIT to send a

DECSYSTEM-20 KERMIT Page 48 group of files.

Text Files and Binary Files

The DEC-20, like most computers, has a file system with its own peculiarities. Like many other systems, the DEC-20 makes a distinction between text files and binary files. Text files are generally those composed only of printing characters (letters, digits, and punctuation) and "carriage control" characters (carriage return, line feed, form feed, tab). Text files are designed to be read by people. Binary files are designed to be read by a computer program, and may have any contents at all. If you use the DEC-20 TYPE command to display a text file on your terminal, the result will be intelligible. If you type a binary file on your terminal, you will probably see mainly gibberish. You can not always tell a text file from a binary file by its name or directory information, though in general files with types like .TXT, .DOC, .HLP are textual (as are "source files" for computer programs like text for- matters and programming language compilers), and files with types like

.EXE, .REL, .BIN are binary.

The DEC-20 has an unusual word size, 36 bits. It differs from most other systems by storing text in 7-bit, rather than 8-bit, bytes. Since text is encoded in the 7-bit ASCII character set, this allows more ef- ficient use of storage. However, the word size is not a multiple of the normal byte size. The DEC-20 therefore stores five 7-bit characters per word, with one bit left over.

It is also possible to store files with other byte sizes. The common layouts of bytes within a word are:

7 Text Files: Five 7-bit bytes per word.

+------+------+------+------+------++

| | | | | ||

+------+------+------+------+------++

0 7 14 21 28 35

Normally, bit 35 is unused and set to zero. However, in EDIT

(or SOS, or OTTO) line-numbered files, bit 35 is set to 1 when

the word contains a line number.

8 "Foreign" binary files: Four 8-bit bytes per word.

+-------+-------+-------+-------+---+

| | | | | |

+-------+-------+-------+-------+---+

0 8 16 24 32 35

Bits 32-35 are unused.

DECSYSTEM-20 KERMIT Page 49

36 "Native" binary files: One 36-bit byte per word.

+-----------------------------------+

| |

+-----------------------------------+

0 35

All bits are used.

The minimum unit of disk allocation on the DEC-20 is a page, 512 36-bit words, or 2560 7-bit characters, or 2048 8-bit bytes. Any file that contains at least one bit of information occupies at least a full page on the disk. The directory information for a file includes the number of pages occupied on the disk, the bytesize of the file, and the number of bytes of that size which are in the file. This information can be seen by using the DEC-20 VDIRECTORY command, for instance

@vdir foo.*

PS:<MY-DIRECTORY>

Name Protection Pages Bytes(Size) Creation

FOO.COM.1;P774242 1 384(8) 27-Dec-83

MAC.1;P774242 1 152(7) 27-Dec-83

.REL.1;P774242 1 39(36) 27-Dec-83

.EXE.1;P774242 2 1024(36) 27-Dec-83

Total of 5 pages in 4 files

In this example, FOO.MAC occupies 1 page, and is composed of 152 7-bit bytes. This file is textual (program source for the MACRO assembler),

152 characters long. Programs which read text files (such as text editors, program compilers, the TYPE command, etc) determine the end of a file from the byte count specified in the directory. KERMIT-20 deter- mines the end of file in the same way, so although FOO.MAC occupies an entire 2560-byte page of storage, only the first 152 characters are transmitted. Binary files, such as FOO.EXE (an executable DEC-20 program), tend to occupy full pages. In this case too, KERMIT-20 uses the byte count to determine the end of file.

Why do you need to know all this? In most cases, you don't. It depends on whether you are using the DEC-20 as your "home base".

Using a Microcomputer to Archive DEC-20 Files

Most computers (other than the DEC-10 and DEC-20) store characters in

8-bit bytes. Let's call any such system an 8-bit-byte system. This discussion applies to all 8-bit-byte systems, including all popular microcomputers, minicomputers like the DEC PDP-11 and VAX, and mainframes like the IBM 370. For simplicity, we'll focus on microcom- puters.

KERMIT can send any "native" DEC-20 sequential file, text or binary, to an 8-bit-byte system and bring it back to the DEC-20 restored to its original form. If you are using a microcomputer to archive your DEC-20 files, you need never concern yourself with details of byte size or file

DECSYSTEM-20 KERMIT Page 50 format. The same holds true between two DEC-20s, or a DEC-10 and a

DEC-20.

There is, however, one special complication of which you should be aware. Certain microcomputer operating systems, notably CP/M, do not have an entirely satisfactory way of indicating the end of file. The file length is recorded in blocks rather than bytes. For text files, the end of file is marked within a block by inserting a Control-Z after the last data character. Binary files, however, might easily contain

Control-Z characters as data. Therefore, in order not to lose data, these systems must transmit binary files in complete blocks. If the bi- nary file is of foreign origin (for instance, from a DEC-20), and it did not happen to fill up the last block when it was transferred to the micro, then when that file is sent back to the system of origin in

"binary mode," junk will appear at the end (if it is sent back in "text mode," it might be truncated by any data byte that happened to cor- respond to Control-Z). For DEC-20 programs in .EXE format, this generally has no effect on the runnability or behavior of the program.

But for other binary files, particularly internal format numerical data or relocatable program object (.REL) files, the junk could have bad ef- fects. Extraneous data at the end of a .REL file will generally cause

LINK to fail to load the file.

Using the DEC-20 to Archive Microcomputer Files

You can use KERMIT to send textual files from a microcomputer or any

8-bit system to the DEC-20 with no special provisions, since KERMIT-20 stores incoming characters in 7-bit bytes as text unless you explicitly instruct it otherwise. But KERMIT-20 has no automatic way of distin-

12 guishing an incoming binary file from an incoming text file. Binary files from 8-bit-byte systems generally contain significant data in the

8th bit, which would be lost if the incoming characters were stored in

7-bit bytes, rendering the file useless when sent back to the original system. Thus if you want to use KERMIT to store foreign 8-bit binary data on the DEC-20, you must tell it to store such files with a bytesize of 8 rather than 7. This can be the source of much confusion and incon- venience. In particular, you cannot use a "wildcard send" command to send a mixture of text and binary files from an 8-bit-byte system to the

DEC-20; rather, you must send all text files with KERMIT-20's file bytesize set to 7, and all 8-bit binary files with the bytesize set to

8.

Once you get the foreign binary file into the DEC-20, stored with the correct bytesize (as FOO.COM is stored in the example above), you need take no special measures to send it back to its system of origin. This is because KERMIT-20 honors the bytesize and byte count from the direc- tory. For instance, if you told KERMIT-20 to SEND FOO.*, every file in the example above would be transmitted in the correct manner, automati- cally.

_______________

12

Unless the incoming file has an "ITS Binary Header"; see below.

DECSYSTEM-20 KERMIT Page 51

Files KERMIT-20 Cannot Handle

The KERMIT protocol can only accommodate transfer of sequential files, files which are a linear sequence of bytes (or words).

Some files on the DEC-20 are not sequential, and cannot be successfully sent or received by KERMIT-20. These include directory files, files with holes (missing pages), ISAM files, and RMS files. These files re- quire external information (kept in the DEC-20's file descriptor block and/or index table) in order to be reconstructed; when sending files,

KERMIT-20 presently transmits only the file name and the contents of the file. External control information (file attributes) are not trans- mitted.

6.2. Program Operation

Kermit-20's prompt is "Kermit-20>". Kermit-20 will accept a single com- mand on the Exec command line, like this:

@

@kermit send foo.bar

the file is sent

@ or you can run the program interactively to issue several commands, like this:

@

@kermit

TOPS-20 KERMIT version 4.1(236)

Kermit-20>send foo.*

files are sent

Kermit-20>statistics

performance statistics are printed

Kermit-20>receive

files are received

Kermit-20>exit

@

During interactive operation, you may use the TOPS-20 help ("?") and

recognition (ESC) features freely while typing commands. A question mark typed at any point in a command displays the options available at that point; typing an ESC character causes the current keyword or filename to be completed (or default value to be supplied), and a "guide word" in parentheses to be typed, prompting you for the next field. If

DECSYSTEM-20 KERMIT Page 52 you have not typed sufficient characters to uniquely specify the keyword or filename (or if there is no default value) then a beep will be sounded and you may continue typing.

Command keywords may be abbreviated to their shortest prefix that sets them apart from any other keyword valid in that field.

If you have a file called KERMIT.INI in your login directory, KERMIT-20 will execute an automatic TAKE command on it upon initial startup.

KERMIT.INI may contain any KERMIT-20 commands, for instance SET com- mands, or DEFINEs for SET macros to configure KERMIT-20 to various sys- tems or communications media.

KERMIT-20 provides most of the commands possible for an "ideal" KERMIT program, as described in the main part of the KERMIT User Guide. The following sections will concentrate on system-dependent aspects of

KERMIT-20.

KERMIT-20 disables terminal links, advice, and system messages in order to minimize interference with data transfer (and restores these to their previous value upon completion of a transfer). However, certain mes- sages cannot be disabled by KERMIT because they are issued by KERMIT's superior controlling process, the TOPS-20 EXEC. These include mail notifications and alerts. Before running KERMIT-20 to transfer files, you should SET NO MAIL-WATCH and SET NO ALERT.

6.3. Remote and Local Operation

KERMIT-20 normally runs in remote mode, with the user sitting at a PC.

But KERMIT-20 can also run in local mode. Local operation of KERMIT-20 is useful if the DEC-20 has an autodialer, or a hardwired connection to another computer. When in local mode, file transfer takes place over an assigned TTY line, and KERMIT-20 is free to update your screen with status information, and to listen to your keyboard for interrupt charac- ters.

Local Operation of KERMIT-20:

DECSYSTEM-20 KERMIT Page 53

DECSYSTEM-20

+---------------------------------------+

| |

| +--------------------+ |

| | Your Job | |

| | | |

| | +------------+ | <--Commands | Your Job's

| | | KERMIT-20 +---+--------------+-----------------O You

| | | | | Display---> | Controlling TTY

| | | | | |

| | | | | |

| | | | | <--Packets | Kermit's

| | | +---+--------------+-----------------> Remote

| | +------------+ | Packets--> | Assigned TTY System

| | | |

| +--------------------+ |

| |

+---------------------------------------+

KERMIT-20 enters local mode when you issue a SET LINE n command, where n is the octal TTY number of any line other than your own controlling ter- minal.

6.4. Conditioning Your Job for Kermit

Kermit-20 does as much as it can to condition your line for file trans- fer. It saves all your terminal and link settings, and restores them after use. However, there are some sources of interference over which

Kermit-20 can have no control. In particular, messages issued by supe- rior or parellel forks could become mingled with Kermit packets and slow things down or stop them entirely. For this reason, before using

Kermit-20 for any extended period, you should:

- Type the Exec commands SET NO MAIL-WATCH and SET NO ALERTS

- Make sure you don't have any print or batch jobs pending that

were submitted with the /NOTIFY option.

After running Kermit, you can restore your mail-watch and alerts.

6.5. KERMIT-20 Commands

This section describes the KERMIT-20 commands, in detail where they dif- fer from the "ideal" KERMIT, briefly where they coincide.

THE SEND COMMAND

Syntax:

Sending a single file:

SEND nonwild-filespec1 (AS) [filespec2]

DECSYSTEM-20 KERMIT Page 54

Sending multiple files:

SEND wild-filespec1 (INITIAL) [filespec2]

The SEND command causes a file or file group to be sent from the DEC-20 to the other system. There are two forms of the command, depending on whether filespec1 contains wildcard characters ("*" or "%"). KERMIT-20 automatically recognizes the two cases and issues the appropriate guide word, (AS) or (INITIAL), depending on the form of filespec1.

Sending a File Group

If filespec1 contains wildcard characters then all matching files will be sent, in alphabetical order (according to the ASCII collating sequence) by name. If a file can't be opened for read access, it will be skipped. The initial file in a wildcard group can be specified with the optional filespec2. This allows a previously interrupted wildcard transfer from where it left off, or it can be used to skip some files that would be transmitted first.

Sending a Single File

If filespec1 does not contain any wildcard characters, then the single file specified by filespec1 will be sent. Optionally, filespec2 may be used to specify the name under which the file will arrive at the target system; filespec2 is not parsed or validated in any way by KERMIT-20, but lower case letters are raised to upper case, and leading

"whitespace" (blanks and tabs) are discarded. If filespec2 is not

13 specified, KERMIT-20 will send the file with its own name.

SEND Command General Operation

Files will be sent with their DEC-20 filename and filetype (for instance

FOO.BAR, no device or directory field, no generation number or attributes). If you expect to be sending files whose names contain characters that would be illegal in filenames on the target system, and you know that the KERMIT on the target system does not have the ability to convert incoming filenames, you can issue the SET FILE NAMING

NORMAL-FORM command to have KERMIT-20 replace suspect characters by X's.

Each file will be sent according to its bytesize and byte count from the directory unless you specify otherwise using SET FILE BYTESIZE, or un- less the file has an "ITS Binary" header. If the bytesize is 8, then four 8-bit bytes will be sent from each DEC-20 36-bit word, and the low order four bits will be skipped. If other than 8, then five 7-bit bytes will be sent from each word, with the 8th bit of the 5th character set

_______________

13

Control-V's, which are used to quote otherwise illegal characters in

DEC-20 file specifications, are stripped.

DECSYSTEM-20 KERMIT Page 55

14 to the value of the remaining bit ("bit 35") from the word.

If communication line parity is being used (see SET PARITY), KERMIT-20 will request that the other KERMIT accept a special kind of prefix nota- tion for binary files. This is an advanced feature, and not all KERMITs have it; if the other KERMIT does not agree to use this feature, binary files cannot be sent correctly. This includes executable programs (like

DEC-20 .EXE files, CP/M .COM files), relocatable object modules (.REL files), as well as text files with line sequence numbers.

KERMIT-20 will also ask the other KERMIT whether it can handle a special prefix encoding for repeated characters. If it can, then files with long strings of repeated characters will be transmitted very ef- ficiently. Columnar data, highly indented text, and binary files are the major beneficiaries of this technique.

If you're running KERMIT-20 locally, for instance dialing out from the

DEC-20 to another system using an autodialer, you should have already run KERMIT on the remote system and issued either a RECEIVE or a SERVER command. Once you give KERMIT-20 the SEND command, the name of each file will be displayed on your screen as the transfer begins; a "." will be displayed for every 5 data packets sucessfully sent, and a "%" for every retransmission or timeout that occurs (you may also elect other typeout options with the SET DEBUG command). If the file is success- fully transferred, you will see "[OK]", otherwise there will be an error message. When the specified operation is complete, the program will sound a beep. If you see many "%" characters, you are probably suffer- ing from a noisy connection. You may be able to cut down on the retransmissions by using SET SEND PACKET-LENGTH to decrease the packet length; this will reduce the probability that a given packet will be corrupted by noise, and reduce the time required to retransmit a cor- rupted packet.

During local operation, you can type Control-A at any point during the transfer to get a brief status report. You may also type Control-X or

Control-Z to interrupt the current file or file group.

THE RECEIVE COMMAND

Syntax: RECEIVE [filespec]

The RECEIVE command tells KERMIT-20 to receive a file or file group from the other system. If only one file is being received, you may include the optional filespec as the name to store the incoming file under; otherwise, the name is taken from the incoming file header. Even if the

_______________

14

This is the same method used by the DEC-20 to encode 36-bit data on

"ANSI-ASCII" tapes. It allows not only DEC-20 binary files, but also the line-sequence-numbered files produced by EDIT, SOS, or OTTO, which use bit 35 to distinguish line numbers from text, to be sent and retrieved correctly.

DECSYSTEM-20 KERMIT Page 56 name in the header is not a legal TOPS-20 file name, KERMIT-20 will store it under that name, in which case you can refer to it later only by quoting each illegal character (spaces, control characters, etc) with

Control-V. If for some reason an incoming filename simply cannot be converted to legal form, the file will be saved as

-UNTRANSLATABLE-FILENAME-.KERMIT (new generation). You may also use SET

FILE NAMING NORMAL-FORM to have KERMIT-20 choose more conventional names for incoming files.

If an incoming file has the same name as an existing file, KERMIT-20 just creates a new generation of the same name and type, for instance

FOO.BAR.3, FOO.BAR.4. The oldest generation will be automatically deleted, but you can still UNDELETE it.

Incoming files will all be stored with the prevailing bytesize, 7 by default, which is appropriate for text files. If you are asking

KERMIT-20 to receive binary files from a microcomputer or other 8-bit system, you must first type SET FILE BYTESIZE 8. Otherwise, the 8th bit of each byte will be lost and the file will be useless when sent back to the system of origin.

If you have SET PARITY, then 8th-bit prefixing will be requested. If the other side cannot do this, binary files cannot be transferred cor- rectly. In all cases, KERMIT-20 will request the other KERMIT to com- press repeated characters; if the other side can do this (not all KER-

MITs know how) there may be a significant improvement in transmission speed.

If an incoming file does not arrive in its entirety, KERMIT-20 will nor- mally discard it; it will not appear in your directory. You may change this behavior by using the command SET INCOMPLETE KEEP, which will cause as much of the file as arrived to be saved in your directory.

If you are running KERMIT-20 locally, you should already have issued a

15

SEND command to the remote KERMIT, and then escaped back to DEC-20

Kermit. As files arrive, their names will be displayed on your screen, along with "." and "%" characters to indicate the packet traffic; you can type Control-A during the transfer for a brief status report.

If a file arrives that you don't really want, you can attempt to cancel it by typing Control-X; this sends a cancellation request to the remote

Kermit. If the remote Kermit understands this request (not all im- plementations of Kermit support this feature), it will comply; otherwise it will continue to send. If a file group is being sent, you can re- quest the entire group be cancelled by typing Control-Z.

_______________

15

not SERVER -- use the GET command to receive files from a KERMIT server.

DECSYSTEM-20 KERMIT Page 57

THE GET COMMAND

Syntax: GET [remote-filespec]

The GET command requests a remote KERMIT server to send the file or file group specified by remote-filespec. This command can be used only when

KERMIT-20 is local, with a KERMIT server on the other end of the line specified by SET LINE. This means that you must have CONNECTed to the other system, logged in, run KERMIT there, issued the SERVER command, and escaped back to the DEC-20.

The remote filespec is any string that can be a legal file specification for the remote system; it is not parsed or validated locally. If you need to include otherwise illegal characters such as "!" or ";" (the normal command comment delimeters), "?" (the command help character),

"@" (the indirect command file indicator), or certain control charac- ters, then you should precede each such character by a Control-V.

Kermit-20 will discard these Control-V quoting prefixes before sending the file specification to the remote host.

If you want to store the incoming file name with a different name than the remote host sends it with, just type GET alone on a line; Kermit-20 will prompt you separately for the source (remote) and destination

(local) file specification. If more than one file arrives, only the first one will be stored under the name given; the rest will be stored under the names they are sent with. Example:

Kermit-20>get

Remote Source File: profile exec a1

Local Destination File: profile.exec

As files arrive, their names will be displayed on your screen, along with "." and "%" characters to indicate the packet traffic. As in the

RECEIVE command, you may type Control-A to get a brief status report, ^X to request that the current incoming file be cancelled, ^Z to request that the entire incoming batch be cancelled.

If the remote KERMIT is not capable of server functions, then you will probably get an error message back from it like "Illegal packet type".

In this case, you must connect to the other Kermit, give a SEND command, escape back, and give a RECEIVE command.

THE SERVER COMMAND

The SERVER command puts a remote KERMIT-20 in "server mode", so that it receives all further commands in packets from the local KERMIT. The

KERMIT-20 server is capable (as of this writing) of executing many remote server commands, including SEND, GET, FINISH, BYE, REMOTE DIREC-

TORY, REMOTE CWD, REMOTE SPACE, REMOTE DELETE, REMOTE TYPE, REMOTE HELP.

Any nonstandard parameters should be selected with SET commands before putting KERMIT-20 into server mode, in particular the file bytesize.

The DEC-20 Kermit server can send most files in the correct manner automatically, by recognizing the DEC-20 file bytesize. However, if you need to ask the DEC-20 KERMIT server to receive binary files from an

DECSYSTEM-20 KERMIT Page 58

8-bit-byte system (that is, from almost any system that's not a DEC-10 or DEC-20) you must issue the SET FILE BYTESIZE 8 command before putting it into server mode, and then you must only send 8-bit binary files.

You cannot send a mixture of text files and 8-bit binary files to a

KERMIT-20 server.

COMMANDS FOR SERVERS

When running in local mode, KERMIT-20 allows you to give a wide range of commands to a remote KERMIT server, with no guarantee the that the remote server can process them, since they are all optional features of the protocol. Commands for servers include the standard SEND, GET, BYE, and FINISH commands, as well as the REMOTE command, which has various options.

Syntax: REMOTE command

Send the specified command to the remote server. If the server does not understand the command (all of these commands are optional features of the KERMIT protocol), it will reply with a message like "Unknown KERMIT server command". If does understand, it will send the results back, and they will be displayed on the screen. The REMOTE commands are:

CWD [directory] Change Working Directory. If no directory name is

provided, the server will change to the default or home

directory. Otherwise, you will be prompted for a

password, and the server will attempt to change to the

specified directory. The password is entered on a

separate line, and does not echo as you type it. If ac-

cess is not granted, the server will provide a message

to that effect.

DELETE filespec Delete the specified file or files. The names of the

files that are deleted will appear on your screen.

DIRECTORY [filespec]

The names of the files that match the given file

specification will be displayed on your screen, perhaps

along with size and date information for each file. If

no file specification is given, all files from the cur-

rent directory will be listed.

HELP Provide a list of the functions that are available from

the server.

HOST [command] Pass the given command to the server's host command

processor, and display the resulting output on your

screen.

SPACE Provide information about disk usage in the current

directory, such as the quota, the current storage, the

amount of remaining free space.

TYPE filespec Display the contents of the specified file on your

screen.

DECSYSTEM-20 KERMIT Page 59

THE LOCAL COMMAND

Syntax: LOCAL [command]

Execute the specified command on the local system -- on the DEC-20 where

KERMIT-20 is running. These commands provide some local file management capability without having to leave the KERMIT-20 program.

CWD [directory] Change working directory, or, in DEC-20 terminology,

CONNECT to the specified directory.

DELETE filespec Delete the specified file or files, but do not expunge

them.

DIRECTORY [filespec]

Provide a directory listing of the specified files.

RUN [filespec] Attempts to run the specified file, which must be in

".EXE" format (.EXE is the default filetype), in an in-

ferior fork. Control returns to KERMIT-20 when the

program terminates. Once you have used this command,

you can restart the same program by issuing a RUN com-

mand with no arguments. If you RUN SYSTEM:EXEC, then

you will be able to issue TOPS-20 commands without leav-

ing KERMIT; you can get back to KERMIT from the EXEC by

typing the EXEC POP command. You can also use the RUN

command to supply new functions to KERMIT by writing

little programs in the language of your choice, for in-

stance to conduct a signon dialog with a remote system

when dialing out.

SPACE Show how much space is used and remaining in the current

directory.

TYPE Display the contents of the specified file or files at

your terminal. This works like the DEC-20 TYPE command,

except that if a file has a bytesize of 8, KERMIT-20

will do 8-bit input from it rather than 7-bit. Also,

the DEC-20 Control-O command discards output only from

the file currently being displayed; if multiple files

are being typed, then output will resume with the next

file.

The LOCAL commands may also be used without the "LOCAL" prefix.

THE CONNECT COMMAND

Syntax: CONNECT [number]

Establish a terminal connection to the system connected to the octal TTY

number specified here or in the most recent SET LINE command, using full duplex echoing and no parity unless otherwise specified in previous SET commands. Get back to KERMIT-20 by typing the escape character followed by the letter C. The escape character is Control-Backslash (^\) by default. When you type the escape character, several single-character

DECSYSTEM-20 KERMIT Page 60 commands are possible:

C Close the connection and return to KERMIT-20.

S Show status of the connection; equivalent to SHOW LINE.

P Push to a new Exec. POP from the Exec to get back to the connec-

tion.

Q If a session log is active, temporarily Quit logging.

R Resume logging to the session log.

B Send a simulated BREAK signal.

? List all the possible single-character arguments.

^\ (or whatever you have set the escape character to be)

Typing the escape character twice sends one copy of it to the con-

nected host.

You can use the SET ESCAPE command to define a different escape charac- ter, and SET PARITY, SET DUPLEX, SET HANDSHAKE, SET FLOW, and SET SPEED to change those communication-line-oriented parameters. In order for the simulated BREAK signal to work, TOPS-20 must know the speed of the terminal. If it does not, you may use the SET SPEED command.

KERMIT-20 does not have any special autodialer interface. It assumes that the connection has already been made and the line assigned.

THE HELP COMMAND

Syntax: HELP [topic [subtopic]]

Typing HELP alone prints a brief summary of KERMIT-20 and its commands.

You can also type

HELP command for any Kermit-20 command, e.g. "help send" or "help set parity" to get more detailed information about a specific command. Type

HELP ? to see a list of the available help commands.

THE TAKE COMMAND

Syntax: TAKE filespec

Execute KERMIT-20 commands from the specified file. The file may con- tain contain any valid KERMIT-20 commands, including other TAKE com- mands; command files may be nested up to a depth of 20.

DECSYSTEM-20 KERMIT Page 61

THE EXIT AND QUIT COMMANDS

Syntax: EXIT

Exit from KERMIT-20. You can CONTINUE the program from the TOPS-20

Exec, provided you haven't run another program on top of it. You can also exit from KERMIT-20 by typing one or more control-C's, even if it's in the middle of transferring a file. KERMIT-20 will always restore your terminal to its original condition, and you will be able to CON-

TINUE the program to get back to "KERMIT-20>" command level with current settings intact.

QUIT is a synonym for EXIT.

THE SET COMMAND

Syntax: SET parameter [option [value]]

Establish or modify various parameters for file transfer or terminal connection. You can examine their values with the SHOW command. The following parameters may be SET:

BREAK Adjust the BREAK simulation parameter

BLOCK-CHECK Packet transmission error detection method

DEBUGGING Record or display state transitions or packets

DELAY How long to wait before starting to send

DUPLEX For terminal connection, FULL or HALF

ESCAPE Character for terminal connection

FILE For setting file parameters like byte size

FLOW-CONTROL For enabling or disabling XON/XOFF flow control

HANDSHAKE For turning around half duplex communication line

IBM For communicating with an IBM mainframe

INCOMPLETE What to do with an incomplete file

ITS-BINARY For recognizing a special 8-bit binary file format

LINE TTY line to use for file transfer or CONNECT

PARITY Character parity to use

PROMPT Change the program's command prompt

RECEIVE Various parameters for receiving files

RETRY How many times to retry a packet before giving up

SEND Various parameters for sending files

SPEED Baud rate of communication line

TVT-BINARY For negotiating binary mode on ARPANET

The DEFINE command may be used to compose "macros" by combining SET com- mands. Those SET commands which differ from the "ideal" KERMIT are now described in detail.

SET BREAK

Syntax: SET BREAK n Specify the number of nulls to be sent at 50 baud to simulate a BREAK signal when connected to a remote host via SET LINE and

CONNECT.

DECSYSTEM-20 KERMIT Page 62

SET DEBUG

Syntax: SET DEBUG options

Record the packet traffic, either on your terminal or in a file. Some reasons for doing this would be to debug a version of KERMIT that you are working on, to record a transaction in which an error occurred for evidence when reporting bugs, or simply to vary the display you get when running KERMIT-20 in local mode. Options are:

STATES Show Kermit state transitions and packet numbers

(brief).

PACKETS Display each incoming and outgoing packet (lengthy).

OFF Don't display or record debugging information (this is

the normal mode). If debugging was in effect, turn it

off and close any log file.

The debugging information is recorded in the file specified by the most recent LOG DEBUGGING command.

SET ESCAPE

SET ESCAPE octal-number

Specify the control character you want to use to "escape" from remote connections back to KERMIT-20. The default is 34 (Control-\). The num- ber is the octal value of the ASCII control character, 1 to 37 (or 177), for instance 2 is Control-B. After you type the escape character, you must follow it by a one of the single-character "arguments" described under the CONNECT command, above.

SET EXPUNGE

SET EXPUNGE ON or OFF

Tell whether you want a DELETE command (either the LOCAL DELETE command or a REMOTE DELETE command sent to a KERMIT-20 server) to expunge files as it deletes them. On the DEC-20, a deleted file continues to take up space, and may be "undeleted" at a later time in the same session. To expunge a deleted file means to remove it completely and irrevocably, freeing its space for further use. EXPUNGE is OFF by default; deleted files are not automatically expunged. SET EXPUNGE applies only to files that are deleted explicitly by KERMIT-20, and not to files that are im- plicitly deleted when new generations of existing files are created.

SET FILE

Syntax: SET FILE parameter keyword

Establish file-related parameters:

DECSYSTEM-20 KERMIT Page 63

BYTESIZE keyword or number

Byte size for DEC-20 file input/output. The choices are SEVEN

(7), EIGHT (8), and AUTO.

SEVEN (or 7) Always store or retrieve five 7-bit bytes per

word. When sending a file, ignore the file bytesize and

do 7-bit input from the file. There would be no reason

to use this option except to explicitly force an 8-bit

file to be treated as a 7-bit file.

EIGHT (or 8) Always store or retrieve four 8-bit bytes per

word. When sending a file, ignore the file bytesize and

do 8-bit input from the file. This command is necessary

when receiving binary files from 8-bit-byte systems,

such as most microcomputers.

AUTO Equivalent to SEVEN for incoming files, and for outgoing

files means to use EIGHT if the DEC-20 file bytesize (as

shown by the Exec VDIR command) is 8, otherwise use

SEVEN. The default is AUTO.

The DEC-20 can send any mixture of file types in the correct way

automatically, but you must set the file bytesize to 8 for any

incoming 8-bit binary files, and to AUTO (i.e. 7) for any incom-

ing text files or DEC-20 binary files.

NAMING UNTRANSLATED or NORMAL-FORM

If NORMAL-FORM the names of incoming or outgoing files will be

converted to contain only uppercase letters, digits, and at most

one period; any other characters will be translated to "X". If

UNTRANSLATED, filenames will be sent and used literally. UN-

TRANSLATED is the default.

SET IBM

Syntax: SET IBM ON or OFF

SET IBM is really a predefined SET macro rather than a "hardwired" SET command; it can be redefined or undefined (see DEFINE); as distributed from Columbia, KERMIT-20 defines IBM to be "parity mark, handshake XON, duplex half".

SET IBM should be used when running KERMIT-20 in local mode, connected to an IBM or similar mainframe. If you have redefined the SET IBM macro, then your parameters will be used instead.

SET ITS-BINARY

Syntax: SET ITS-BINARY ON or OFF

Specify whether ITS-Binary file headers are to be recognized or ignored.

By default, they are recognized. ITS binary format is a way (devised at

MIT) of storing foreign 8-bit binary data on a 36-bit machine to allow automatic recognition of these files when sending them out again, so

DECSYSTEM-20 KERMIT Page 64 that you don't have to depend on the file byte size, or to issue ex- plicit SET FILE BYTESIZE commands to KERMIT.

An ITS format binary file contains the sixbit characters "DSK8" left-adjusted in the first 36-bit word. If ITS-BINARY is ON, then

KERMIT-20 will send any file starting with this "header word" using

8-bit input from the file even if the file bytesize is not 8, and will not send the header word itself. KERMIT-20 will also store any incoming file that begins with that header word using 8-bit bytesize, again dis- carding the header word itself. If ITS-BINARY is OFF, then the header word, if any, will be sent or kept, and i/o will be according to the setting of FILE BYTESIZE.

This facility is provided for compatibility with the file formats used on certain public-access CP/M libraries.

SET LINE

Syntax: SET LINE [octal-number]

Specify the octal TTY number to use for file transfer or CONNECT. If you issue this command, you will be running KERMIT-20 locally, and you must log in to the remote system and run Kermit on that side in order to transfer a file. If you don't issue this command, KERMIT-20 assumes it is running remotely, and does file transfer over its job's controlling terminal line. You can also select the line directly in the CONNECT command; the command

CONNECT 12 is equivalent to

SET LINE 12

CONNECT

If you type SET LINE with no number argument, you will deassign any pre- vious assigned line and revert to remote mode.

The SHOW LINE command will display the currently selected communication line and its charactistics, including parity, duplex, handshake, flow control, the speed if known, whether carrier is present (if it is a modem-controlled line), and whether KERMIT-20 is in local or remote mode.

SET RECEIVE

In addition to the full complement of SET RECEIVE commands described in the main part of the manual, you may also SET RECEIVE SERVER-TIMEOUT to a value between 0 and 94. This specifies the number of seconds between

timeouts during server command wait, 0 specifies that no timeouts should occur during server command wait. When a KERMIT server times out, it sends a NAK packet. Some systems cannot clear piled-up NAKs from their input buffers; if you're using such a system to communicate with a

KERMIT-20 server, and you expect to be leaving the server idle for long

DECSYSTEM-20 KERMIT Page 65 periods of time, you should use this command to turn off server command- wait timeouts.

SET SPEED

Syntax: SET SPEED n

Set the baud rate of the currently selected communication to n, the decimal baud rate, for instance 300, 1200, 4800. When operating in local mode, it may be necessary to issue this command in order to enable

BREAK simulation.

SET TVT-BINARY

Syntax: SET TVT-BINARY ON or OFF

Only for users running KERMIT-20 on an ARPANET DEC-20, signed on to an

ARPANET virtual terminal (TVT) from another host or through an ARPANET

TAC. SET TVT ON causes KERMIT-20 to negotiate binary mode (8-bit) com- munication with the ARPANET during file transfer. Without this command, file transfer through a TVT would not work in most cases.

TVT-BINARY is OFF by default. If you normally use KERMIT-20 through the

ARPAnet, you can put the command SET TVT-BINARY ON into your KERMIT.INI file.

CAUTION: This facility requires certain features in the Release 5

TOPS-20 ARPANET monitor, which may not be present in releases dis- tributed by DEC. See the KERMIT-20 source code for details.

THE DEFINE COMMAND

Syntax: DEFINE macroname [set-option [, set-option [...]]]

The DEFINE command is available in KERMIT-20 for building "macros" of

SET commands. The macro name can be any keyword-style character string, and the set options are anything you would type after SET in a SET com- mand; several set options may be strung together, separated by commas.

Example:

define notimeout send timeout 0, receive timeout 0

Macro definitions may not include macro names. You can list all your macros and their definitions with the SHOW MACROS command. You can list a particular macro definition with HELP SET macroname.

DECSYSTEM-20 KERMIT Page 66

THE SHOW COMMAND

Syntax: SHOW [option]

The SHOW command displays various information:

DAYTIME Current date, time, phase of moon.

DEBUGGING Debugging mode in effect, if any.

FILE-INFO Byte size for DEC-20 file i/o, incomplete file disposi-

tion.

LINE TTY line, parity, duplex, flow control, handshake, es-

cape character, speed (if known), and session loggin in-

formation. Note that before release 6.0 of TOPS-20, the

DEC-20 does not keep a record of the actual baud rate of

a modem-controlled or "remote" TTY line.

MACROS Definitions for SET macros.

PACKET-INFO For incoming and outbound packets. Items under RECEIVE

column show parameters for packets KERMIT-20 expects to

receive, under SEND shows parameters for outgoing pack-

ets.

TIMING-INFO Delays, retries, server NAK intervals.

VERSION Program version of KERMIT-20. This is also displayed

when KERMIT-20 is initially started.

ALL (default) All of the above.

THE STATISTICS COMMAND

Give statistics about the most recent file transfer. For instance, here's what KERMIT-20 displayed after transmitting a short binary file, using repeated-character compression:

Maximum number of characters in packet: 80 received; 80 sent

Number of characters transmitted in 2 seconds

Sent: 34 Overhead: 34

Received: 107 Overhead: -408

Total received: 141 Overhead: -374

Total characters transmitted per second: 70

Effective data rate: 2570 baud

Efficiency: 214.1667 per cent

Interpacket pause in effect: 0 sec

Timeouts: 0

NAKs: 0

Note that the data compression allowed the effective baud rate to exceed the actual speed of the communication line, which in this case happened

DECSYSTEM-20 KERMIT Page 67 to be 1200 baud. The efficiency is displayed only if the actual baud rate is known.

THE LOG COMMAND

Syntax: LOG [option [filespec]]

Log the specified option to the specified file:

SESSION During CONNECT, log all characters that appear on the

screen to the specified file. The session log can be

temporarily turned off during the remote session by

typing the escape character followed by Q (for Quit

logging), and turned on again by typing the escape

character followed by R (for Resume logging). Default

log is SESSION.LOG in the current directory.

TRANSACTIONS During file transfer, log the progress of each file.

The DEC-20 transaction log file looks like this:

KERMIT-20 Transaction Log File, Monday 27-Feb-1984

18:40:13: Opened Log: PS:<TIMREK>SAMPLE.LOG.1

18:40:31: -- Send Begins --

8th bit prefixing: Off

Block check type: 1

18:40:31: Opened File: PS:<SY.FDC>LOGIN.CMD.6

Sending As "LOGIN.CMD"

Sent: 547 7-bit bytes

18:40:34: Closed PS:<SY.FDC>LOGIN.CMD.6

18:40:34: Send Complete

18:40:50: -- Receive Begins --

8th bit prefixing: Off

Block check type: 1

18:40:50: Opened: PS:<TIMREK>AUTOEXEC.BAT.1

Written: 186 7-bit bytes

18:40:51: Closed: PS:<TIMREK>AUTOEXEC.BAT.1

18:40:56: Closed Transaction Log

Transaction logging is recommended for long or un-

attended file transfers, so that you don't have to watch

the screen. The log may be inspected after the transfer

is complete to see what files were transferred and what

errors may have occurred. Default log is

TRANSACTION.LOG in the current directory.

DEBUGGING Log STATES or PACKETS, as specified in the most recent

SET DEBUGGING command, to the specified file. If log

file not specified, then use TTY if local, or

DEBUGGING.LOG in the current directory if remote. If no

SET DEBUGGING command was previously issued, log STATES

to the specified file. Also allow specification of

bytesize for the log file, 7 (normal, default), or 8

DECSYSTEM-20 KERMIT Page 68

(for debugging binary transfers when the parity bit is

being used for data), for instance

LOG DEBUGGING BINARY.LOG 8

A 7-bit log file can be typed, printed, or examined with

a text editor or searching program. An 8-bit log file

can only be examined with a system utility like FILDDT.

When logging packets, each packet is preceded by a

timestamp, the current timeout interval (preceded by a

slash), and "R:" or "S:" to indicate data being received

and sent, respectively. Packet format is described in

the KERMIT Protocol Manual.

SESSION is the default option. Thus the command "LOG" alone will cause

CONNECT sessions to be logged in SESSION.LOG in the current directory.

Any log files are closed when you EXIT or QUIT from KERMIT, and are reactivated if you CONTINUE the program. You may explicitly close a log file and terminate logging with the CLOSE command.

THE CLOSE COMMAND

Syntax: CLOSE [option]

Close the specified log file, SESSION, TRANSACTION, or DEBUGGING, and terminate logging.

6.6. Examples

Here are a few examples of the use of KERMIT-20. Text entered by the user is underlined.

Remote Operation

The following example shows use of KERMIT-20 as a server from an IBM PC.

In this example, the user runs KERMIT on the PC, connects to the DEC-20, and starts KERMIT-20 in server mode. From that point on, the user need never connect to the DEC-20 again. In this example, the user gets a file from the DEC-20, works on it locally at the PC, and then sends the results back to the DEC-20. Note that the user can leave and restart

KERMIT on the PC as often as desired.

A>kermit

Kermit-86>connect

@

@kermit

TOPS-20 KERMIT version 4.1(236)

Kermit-20>server

DECSYSTEM-20 KERMIT Page 69

Kermit Server running on DEC-20 host. Please type your escape

sequence to return to your local machine. Shut down the server by

typing the Kermit BYE command on your local machine.

^[C

Kermit-86>get foo.txt

The transfer takes place.

Kermit-86>exit

A>

A>edit foo.txt ; (or whatever...)

A>

A>kermit

Kermit-86>send foo.txt

The transfer takes place.

Kermit-86>bye

A>

The next example shows the special procedure you would have to use in order to send a mixture of text and binary files from a PC (or an 8-bit- byte system) to the DEC-20. Note that in this case, it's more con- venient to avoid server mode.

Kermit-86>connect

@

@kermit

TOPS-20 KERMIT version 4.1(236)

Kermit-20>receive

^]C

Kermit-86>send *.txt

Textual files are sent.

Kermit-86>connect

Kermit-20>set file bytesize 8

Kermit-20>receive

^]C

Kermit-86>send *.exe

Binary files are sent.

Kermit-86>connect

Kermit-20>exit

@logout

^]C

Kermit-86>exit

A>

DECSYSTEM-20 KERMIT Page 70

Local Operation

In this example, a program DIAL is used to direct an autodialer to call another computer (a DECSYSTEM-10); once the connection is made, DIAL starts KERMIT with an implicit CONNECT command for the appropriate com- munication line. DIAL is not part of KERMIT; if your system has an autodialer, there will be some site-specific procedure for using it.

@dial

Dial>dial stevens

STEVENS, 1-(201) 555-1234, baud:1200

[confirm]

Dialing your number, please hold...

Your party is waiting on TTY11:.

@

@kermit

TOPS-20 KERMIT version 4.1(236)

Kermit-20>connect 11

[KERMIT-20: Connecting over TTY11:, type <CTRL-\>C to return]

CONNECTING TO HOST SYSTEM.

Stevens T/S 7.01A(10) 20:20:04 TTY41 system 1282

Connected to Node DN87S1(101) Line # 57

Please LOGIN or ATTACH

.log 10,35

JOB 51 Stevens T/S 7.01A(10) TTY41

Password:

20:20 15-Dec-83 Thur

.r new:kermit

TOPS-10 KERMIT version 2(106)

Kermit-10>server

[Kermit Server running on the DEC host. Please type your escape

sequence to return to your local machine. Shut down the server by

typing the Kermit BYE command on your local machine.]

^YC

[KERMIT-20: Connection Closed. Back at DEC-20.]

DECSYSTEM-20 KERMIT Page 71

Kermit-20>set file bytesize 8

Kermit-20>get setdtr.cmd

^A for status report, ^X to cancel file, ^Z to cancel batch.

SETDTR.CMD.7 ^A

Receiving SETDTR.CMD.7, file bytesize 8

(repeated character compression)

At page 1

Files: 0, packets: 1, chars: 66

NAKs: 0, timeouts: 0

.[OK]

Kermit-20>bye

Job 51 User F DA CRUZ [10,35]

Logged-off TTY41 at 20:22:58 on 15-Dec-83

Runtime: 0:00:01, KCS:33, Connect time: 0:02:39

Disk Reads:72, Writes:4, Blocks saved:160

....

Hangup? y

Click. Call duration was 193 seconds to area 201.

Dial>exit

Note the use of Control-A to get a status report during the transfer.

6.7. Installation

KERMIT-20 is built from a single MACRO-20 source file, 20KERMIT.MAC. It requires the standard DEC-distributed tools MONSYM, MACSYM, and CMD; the following files should be in SYS: -- MONSYM.UNV, MACSYM.UNV, MACREL.REL,

CMD.UNV, and CMD.REL. The program should work on all TOPS-20 systems as distributed, but many customizations are possible. The site manager may wish to change various default parameters on a site-wide basis; this may be done simply by changing the definitions of the desired symbols, under

"subttl Definitions", and reassembling.

The most notable site dependency is the definition of "SET IBM". As distributed from Columbia, KERMIT-20 defines "SET IBM" in a built-in SET macro definition as "parity mark, duplex half, handshake xon". This definition may be found at MACTAB+1, near the end of the impure data section. It may be changed or deleted, and the program reassembled.

Sites that do not have ARPANET may wish to delete the TVT-BINARY entries from SET command tables, SETABL and SETHLP.

VAX/VMS KERMIT Page 72

7. VAX/VMS KERMIT

Authors: Bob McQueen, Nick Bush, Stevens Institute of Technology

Language: Bliss-32, Common Bliss

Version: 2.0

Date: November 1983

KERMIT for the Digital Equipment Corporation VAX/VMS system is called

"KERMIT-32" since the VAX is DEC's 32-bit line of computers. KERMIT-32 can be run from SYS$SYSTEM:. It will prompt for input from SYS$COMMAND:

.

Kermit-32 can be run in either local or remote modes. In remote mode, transfers take place over the controlling terminal line. Ususally,

Kermit-32 is used in remote mode as a "server", meaning that it will ac- cept commands from the other Kermit. In local mode, Kermit-32 will per- form transfers over a terminal line other than the controlling terminal.

In local mode, Kermit-32 is capable of giving commands to a "server"

Kermit. Note that in order to use Kermit-32 in local mode, the protec- tion code for the terminal to be used must allow the user access. This is set by the system manager. Kermit-32 is put into local mode by using the SET LINE TTcnn: command.

Currently, VMS Kermit does not allocate the terminal line you are using for CONNECT or transfers. Therefore, when going between CONNECT and

SEND or RECEIVE, VMS hangs up the phone for you. This is easily solved by using the DCL ALLOCATE command to allocate the terminal line before entering Kermit.

VMS KERMIT implements a large subset of "ideal" KERMIT, for both remote and local operation.

Here is a summary of the commands of KERMIT-32:

CONNECT [dev:]

The CONNECT command will allow you to connect as a virtual ter-

minal over the line that was specified by the SET LINE command,

or to the terminal line specified in the command. The terminal

line must be one which is accessible to the users process. This

means that the applicable protection code for the terminal must

have been set to allow your process to access it (done by the

system manager). The format of the CONNECT command is:

Kermit-32>CONNECT

or

Kermit-32>CONNECT TTcn:

where TTcn: is the terminal line name to be used.

HELP [keyword [keyword...]]

Give VMS-style help on KERMIT commands.

EXIT, QUIT

Exit from Kermit-32.

VAX/VMS KERMIT Page 73

RECEIVE The RECEIVE command is used to put Kermit-32 into remote mode

waiting for a single file transfer transaction, or to have a

local Kermit-32 request a file from the remote Kermit. If no

file specification is given, Kermit-32 will wait for a file

transfer initialization sequence from the other Kermit. This is

most useful if the other Kermit does not support local server

commands. In order for a file specification to be given,

Kermit-32 must be running as a local Kermit (i.e. a SET LINE

command must have been done). Kermit-32 will then request the

other Kermit (which must be running in server mode) to transfer

the specified file (or set of files) to Kermit-32. The file

specification must be in the format of the system on which the

server Kermit is running. The format of the command is:

Kermit-32>RECEIVE

or

Kermit-32>RECEIVE file-specification

where "file-specification" is any valid file specification on

the system on which the server Kermit is running.

GET filespec

This command is identical to the RECEIVE filespec command. It

is now the preferred command to cause the other Kermit (when

running in server mode) to transmit a file to Kermit-32.

BYE This command will cause Kermit-32 (when in local mode) to tell

the other Kermit (which should be in server mode) to exit from

Kermit and, if applicable, terminate its job (or process, etc.).

When Kermit-32 receives the acknowledgement that this is being

done, it will exit to VMS.

FINISH This command will cause Kermit-32 (when in local mode) to tell

the other Kermit (which should be in server mode) to exit from

Kermit. After receiving the acknowledgement that this is being

done, Kermit-32 will prompt for another command.

LOGOUT This command will cause Kermit-32 (when in local mode) to tell

the other Kermit (which should be in server mode) to exit from

Kermit and, if applicable, terminate its job (or process, etc.).

When Kermit-32 receives the acknowledgement that this is being

done, it will prompt for another command.

SEND The SEND command will allow you to send a file(s) to the other

Kermit. The SEND command will allow file wild card processing

as is found in VMS. If Kermit-32 is running in remote mode, the

file will be sent on the controlling terminal line after waiting

the number of seconds specified by the SET DELAY command. This

gives the user time to escape back to the other Kermit and issue

a receive command. If Kermit-32 is running in local mode, the

file will be sent immediately on the terminal line specified by

the SET LINE command. The command format is:

Kermit-32>SEND file-specification

VAX/VMS KERMIT Page 74

Where "file-specification" is any normal VAX/VMS file specifica-

tion.

SERVER This command will cause Kermit-32 to enter server mode. The

other Kermit can then issue server commands to send and receive

files without having to give SEND or RECEIVE commands to

Kermit-32. Kermit-32 may be put into SERVER mode while running

as either a remote Kermit (transmitting over the controlling

terminal line), or as a local Kermit (transmitting over a ter-

minal specified by a SET LINE command). Note that in order to

correctly receive binary files while in SERVER mode, a SET

FILETYPE BINARY must be done first. At this time there is no

way for Kermit-32 to determine whether an incoming file is ASCII

or binary. The format of the command is:

Kermit-32>SERVER

STATUS The current status of Kermit-32 will be displayed. This in-

cludes the number of characters that have been sent and received

from the remote Kermit. Also included is an estimate of the ef-

fective baud rate of

THE SET COMMAND

The SET command is used to set various parameters in Kermit.

BLOCK_CHECK_TYPEkeyword

where keyword is one of:

1_CHARACTER_CHECKSUM or ONE_CHARACTER_CHECKSUM

2_CHARACTER_CHECKSUM or TWO_CHARACTER_CHECKSUM

3_CHARACTER_CRC_CCITT or THREE_CHARACTER_CRC_CCITT

DEBUGGING The SET DEBUGGING command is used to set the debug type

out on the user's terminal. The command will accept ei-

ther the keywords ON or OFF. Kermit-32 can only do

debugging type out when running as a local Kermit (SET

LINE command done). This is because the debugging type

out would interfere with the file transfer if it were

sent to the controlling terminal line in remote mode.

Kermit-32>SET DEBUGGING state

Where state is either 'ON' or 'OFF'.

DELAY The DELAY parameter is the number of seconds to wait be-

fore sending data after a SEND command is given. This

is used when Kermit-32 is running in remote mode to al-

low the user time to escape back to the other Kermit and

give a RECEIVE command.

Kermit-32>SET DELAY number-of-seconds

Where number of seconds is the (decimal) number of

seconds to wait before sending data.

VAX/VMS KERMIT Page 75

ESCAPE This command will set the escape character for the CON-

NECT processing. The command will take the octal value

of the character to use as the escape character. This

is the character which is used to "escape" back to

Kermit-32 after using the CONNECT command. It defaults

to CTRL-] (octal 35). It is usually a good idea to set

this character to something which is not used (or at

least not used very much) on the system being to which

Kermit-32 is CONNECTing.

Kermit-32>SET ESCAPE octal-character-value

where octal-character-value is the ASCII value of the

character to use as the escape character (in octal).

FILE_TYPE This command will set the file type that Kermit is

receiving. A file type of ASCII should be used to

receive text files which are to be used as text files on

the VMS system. The file type BINARY should be used for

binary files, such as CP/M .COM files, which need to be

kept in a format that allows the file to be returned

without any changes.

Kermit-32>SET FILE_TYPE type

where type is one of:

ASCII File type ASCII is for text files.

BINARY File type BINARY is for non-text files.

Note that binary files which are

generated on a VMS system cannot be

transferred to another VMS system with-

out losing file attributes. This means

that (for example), an .EXE file cannot

be transmitted with Kermit-32. (This

problem should be resolved in a future

version of Kermit).

IBM_MODE For communicating with IBM mainframes; sets parity MARK,

handshake XON, and local echo during CONNECT.

Kermit-32>SET IBM_MODE keyword

where keyword is either ON or OFF.

INCOMPLETE_FILE_DISPOSITION

The SET INCOMPLETE_FILE_DISPOSITION allows the user to

determine what is done with a file that is not com-

pletely received.

Kermit-32>SET INCOMPLETE_FILE_DISPOSITION keyword

where keyword is either DISCARD or KEEP.

LINE This will set the terminal line that you are using. The

VAX/VMS KERMIT Page 76

terminal line must be one which is accessible to the

user's process. This means that the applicable protec-

tion code for the terminal must have been set to allow

your process to access it (done by the system manager).

You should also ALLOCATE the line from DCL before giving

this command.

Kermit-32>SET LINE device:

The device must be a terminal line (e.g. TTA0:).

LOCAL_ECHO The SET LOCAL_ECHO command specifies whether characters

should be echoed locally when CONNECTing to another sys-

tem.

Kermit-32>SET LOCAL_ECHO keyword

where keyword is either ON (local echo) or OFF (full

duplex, normal case).

MESSAGE This command sets the type of typeout Kermit-32 will do

during transfers in local mode. Kermit-32 can type out

the file specification being transferred, the packet

numbers being sent an received, both or neither. The

default is to type file specifications but not packet

numbers.

Kermit-32>SET MESSAGE type keyword

Where type is either FILE or PACKET, and keyword is ei-

ther ON or OFF.

PARITY This command determines the type of parity to use on the

transmission line. Kermit-32 normally uses characters

which consist of eight data bits with no parity bit.

Kermit-32>SET PARITY keyword

where keyword is NONE (default), MARK, SPACE, EVEN, or

ODD. If any parity other than NONE is specified,

8th-bit-prefixing will be requested for transmission of

binary files.

RETRY This command sets the maximum number of times Kermit-32

should try to send a specific packet.

Kermit-32>SET RETRY keyword number

where keyword is either INITIAL_CONNECTION (for initial

connection packet) or PACKET (for all other packets),

and number is the decimal number of retries to attempt.

RECEIVE It is possible to set various parameters associated with

the receiving of the data from the remote Kermit. SET

RECEIVE will enable you to set the various receive

parameters.

VAX/VMS KERMIT Page 77

PACKET_LENGTH This will set the receive packet length,

between 10 and 96. The default value is

80.

Kermit-32>SET REC PACKET_LEN 60

PADDING This command will set the number of pad-

ding characters that will be sent to the

other Kermit. The default value is 0.

Kermit-32>SET RECEIVE PADDING n

Where n is the decimal number of padding

characters to use.

PADCHAR This parameter is the padding character

that is sent to the remote Kermit. The

parameter must be an octal number in the

range of 0 to 37 or 177. All other

values are illegal. The default value

is 0 (an ASCII NUL).

Kermit-32>SET RECEIVE PADCHAR nnn

where nnn is the ASCII value of the

character to be used as a pad character

(in octal).

START_OF_PACKET This command will set the start of

packet character for Kermit. The start

of packet character must be in the range

of 0 to 36 octal. The default value is 1

(ASCII SOH, CTRL-A). This value should

only be changed if absolutely necessary.

It must be set the same in both Kermits.

Kermit-32>SET REC START_OF_PACK 3

TIMEOUT This will set the number of seconds be-

fore Kermit-32 will time out the attempt

to receive a message. This time out is

used to handle transmission errors which

totally lose a message. The default

value is 15 seconds.

Kermit-32>SET RECEIVE TIMEOUT n

where n is the number of seconds to wait

for a message (in decimal).

END_OF_LINE This will set the end of line character

the Kermit-32 expects to receive from

the remote Kermit. This is the charac-

ter which terminates a packet. The

default value is 15 (ASCII CR, CTRL-M).

VAX/VMS KERMIT Page 78

Kermit-32>SET REC END_OF_LINE nnn

where nnn is the ASCII value of the

character to use for the end of line

character (in octal).

QUOTE This will set the quoting character that

Kermit-32 will expect on incoming mes-

sages. This is the character used to

quote control characters. The default

value is 43 (ASCII "#").

Kermit-32>SET RECEIVE QUOTE nnn

where nnn is the ASCII value of the

quoting character (in octal).

SEND It is possible to set various parameters associated with

the receiving of the data from the remote Kermit. SET

SEND will enable you to set the various SEND parameters.

These parameters should not normally be set, since as

part of the transfer initialization process the two

Kermit's exchange their RECEIVE parameters. The

capability of setting these parameters is provided so

that the transfer initialization can be completed even

if the default parameters are not correct.

PACKET_LENGTH This will set the SEND packet length.

The value for this parameter must be be-

tween 10 and 96. Packet lengths outside

of this range are illegal. The default

value is 80.

PADDING This command will set the number of pad-

ding characters that will be sent to the

other Kermit. The default value is 0.

PADCHAR This parameter is the padding character

that is sent to the remote Kermit. The

parameter must be an octal number in the

range of 0 to 37 or 177. All other

values are illegal. The default value

is 0 (an ASCII NUL).

START_OF_PACKET This command will set the start of

packet character for Kermit. The start

of packet character must be in the range

of 0 to 36 octal. The default value is 1

(ASCII SOH, CTRL-A). This value should

only be changed if absolutely necessary.

It must be set the same in both

Kermit's.

TIMEOUT This will set the number of seconds be-

VAX/VMS KERMIT Page 79

fore Kermit-32 will time out a message

it has sent to the other Kermit. mes-

sage. This time out is used to handle

transmission errors which totally lose a

message. The default value is 15

seconds.

END_OF_LINE This will set the end of line character

the Kermit-32 will send to the remote

Kermit. This is the character which

terminates a packet. The default value

is 15 (ASCII CR, CTRL-M).

QUOTE This will set the quoting character that

Kermit-32 will expect on incoming mes-

sages. This is the character used to

quote control characters. The default

value is 43 (ASCII "#").

The SHOW Command

The SHOW command will allow you to show the various parameters that are set with the SET command.

ALL The SHOW ALL command will cause all of the parameters to

be listed.

BLOCK_CHECK_TYPE

This command will type out what type of block check is

being requested.

COMMUNICATIONS This command will type out the communcations line re-

lated parameters. This includes the terminal line being

used, the parity type, etc.

DEBUGGING The SHOW DEBUGGING command will print the state of the

debugging flag.

DELAY This will display the number of seconds delay that Ker-

mit will use before attempting to send or receive a

file.

ESCAPE This will display the current escape character for the

CONNECT processing.

FILE_PARAMETERS This will display the parameters related to files being

used. This includes the file type and the incomplete

file disposition.

FILE_TYPE This will display the current file type that is used in

sending the file to or receiving the from the micro com-

puter.

INCOMPLETE_FILE_DISPOSITION

This will display the disposition of incompletely

VAX/VMS KERMIT Page 80

received files.

LOCAL_ECHO This will display the status of the local echo flag.

PACKET This will display the current settings of the send and

receive packet parameters.

PARITY This will display the current parity setting.

SEND All of the send parameters will be displayed on the

user's terminal.

RECEIVE The current values of the RECEIVE parameters will be

displayed on the user's terminal. Only the parmeters

that can be set will be displayed.

RETRY This command will show the maximum retry attempts that

Kermit will attempt to send a message the remote.

IBM VM/CMS KERMIT Page 81

8. IBM VM/CMS KERMIT

Author: Daphne Tzoar, Columbia University

Version: ( unnumbered )

Date: February 1983

Written in IBM 370 assembly language to run under VM/CMS on IBM 370- series mainframes (System/370, 303x, 43xx, 308x, ...). These are half duplex systems; the communication line must "turn around" before any data can be sent to it. The fact that a packet has been received from the IBM system is no guarantee that it is ready for a reply. Thus any

Kermit talking to this system must wait for the line turnaround charac- ter (XON) before transmitting the next character.

IBM systems talk to their terminals through a communications front end

(IBM 3705, 3725, COMTEN 3670, etc). These front ends generally insist on using the 8th bit of each character for parity. This means that bi- nary files (files containing other than ordinary letters, digits, punctuation, carriage returns, tabs, and so forth) can not be correctly sent or received by these systems with Kermit (protocol version 1).

The IBM system under VM/CMS is unable to interrupt a read on its

"console". This means that the IBM version of Kermit cannot timeout.

The only way to "timeout" CMS Kermit is from the other side -- typing a carriage return to the micro's Kermit causing it to retransmit its last packet, or an automatic timeout as provided by Kermit-20. For this reason, CMS Kermit waits ten seconds before sending its first packet when sending files from VM/CMS. This gives the user sufficient time to return to the local Kermit and issue the Receive command. Otherwise, a protocol deadlock would arise requiring manual intervention by the user.

Also, VM/CMS stores files as records rather byte streams. VM/CMS Kermit has to worry about assembling incoming data packets into records and stripping CRLFs from incoming lines, and also appending CRLFs to -- and stripping trailing blanks from -- outgoing records.

The VM/CMS file specification is in the form

FILENAME FILETYPE FILEMODE

(abbreviated FN FT FM). FM is equivalent to a device specification on

DEC or microcomputer systems (FN FT FM would translate to FM:FN.FT).

FILENAME and FILETYPE are at most 8 characters in length, each, and

FILEMODE at most 2. When FILEMODE is omitted from a filespec, the user's own disk is assumed. Kermit-CMS sends only FILENAME and

FILETYPE, and converts the intervening blank to a period for com- patibility with most other operating systems. Kermit-CMS Commands:

SEND fn ft [fm]

Send the specified file(s), using * or % as the wildcard charac-

ters (* will match any number of characters while % matches only

one). Kermit-CMS assumes the file is located on the A disk, and

sets the filemode to A1. If, however, the file is located on a

different disk, the filemode must be cited. Also, note that if

you use * for the filemode, Kermit-CMS will send only the first

file that matches. Examples:

IBM VM/CMS KERMIT Page 82

The command SEND CEN SPSS will send CEN SPSS A1. To

send the same file located on your B disk, you must

specify: SEND CEN SPSS B. SEND * FORTRAN will send all

fortran files on your A disk. SEND ABC% EXEC will send

all exec files with a four letter filename beginning

with ABC. If you have the file PLOT SAS on your A disk

and your B disk, SEND PLOT SAS * will send PLOT SAS A1.

RECEIVE [fn ft [fm]]

Receive the file(s) sent from the other Kermit. If a file

specification is not included, Kermit-CMS will use the name(s)

provided by the other Kermit. Use the file specification to in-

dicate a different filename or a disk other than the A disk (in

this case, the file name and type must also be supplied or

= = FM can be used.) Examples:

To receive files using the filename(s) sent by the

micro, use: RECEIVE. To save a file under a different

name, specify: RECEIVE ABC FORTRAN. To save the file

under the same name but on the B disk, specify: RECEIVE

ABC FORTRAN B, or RECEIVE = = B.

SET parameter value

Set the parameter to the specified value. Legal Set commands

are:

RECFM option

Denotes the record format to be used when creating the

file. Only fixed and variable length records are al-

lowed, where variable is the default. Indicate the

desired record format by either an F (fixed) or a V

(variable).

LRECL decimal-number

Indicates the logical record length. The default is 80,

and the maximum allowed is 256.

QUOTE decimal-number

The ASCII value of the control prefix character you wish

to use in place of the default (#). It must be a

single, printable character from among the following:

33-62, 96, or 123-126 (decimal).

END decimal-number

Indicates the ASCII value of the end-of-line character

you choose to send. The default is CR (ASCII 13

decimal), but can be set to any two digit number between

00 and 31 (decimal).

PAC decimal-number

Allows the user to specify the packet size the micro

should use when sending to Kermit-CMS. The range is

26-94, where 94 is the default.

SHOW parameter

Displays the current value of any variable that can be changed

IBM VM/CMS KERMIT Page 83

via the SET command.

STATUS Returns the status of the previous execution of Kermit-CMS.

Therefore, STATUS will either display the message "Kermit com-

pleted successfully", or the last error encountered prior to

aborting.

CMS Issues a CMS command from within Kermit-CMS.

CP Issues a CP command from within Kermit-CMS.

? Lists all legal Kermit-CMS commands.

This is a list of other salient facts about Kermit-CMS:

1. The commands are supplied with a help option, so a question

mark can be typed to get the appropriate format or a list of

options. The question mark, however, must be followed by a

carriage return; Kermit-CMS will respond and display the

prompt again. For instance, SET ? will list all valid op-

tions for the SET command.

2. When receiving files, if the record format is fixed, any

record longer than the logical record length will be trun-

cated. If the record format is variable, the record length

can be as high as 256. For sending files, the maximum record

length is 256.

3. Before connecting to the IBM mainframe from other systems

(like the various microcomputer and PC Kermits, DEC-20 Ker-

mit, etc), you should set the IBM flag ON so that echoing,

parity, and handshaking can be done the way the IBM system

likes.

4. Note that "(" and ")" act as word separators on the input

line. Therefore, if you try to set the quote character to

"(*" or "*(", for example, only the first character will be

used.

5. Since some Kermits do not send an error packet when they

"abort", Kermit-CMS does not always know the micro has

stopped sending it information. Therefore, when you connect

back to the IBM, Kermit-CMS may still be sending packets

(they will appear on the screen). The user must hit a car-

riage return until Kermit-CMS has sent the maximum number of

packets allowed and aborts. The error message, however, will

not indicate that communication stopped because the micro

aborted, but rather that no start of header character was

found.

6. The minimum send packet size Kermit-CMS will allow is 26.

This is necessary to avoid an error while sending the

filename or an error packet. If the micro tries to set the

value to be less than 26, Kermit-CMS will immediately abort

with an error of "Bad send-packet size."

IBM VM/CMS KERMIT Page 84

7. While the IBM's communication front end processor translates

all incoming characters from ASCII terminals to EBCDIC,

Kermit-CMS translates the data it reads back to ASCII

(characters not representable in ASCII are replaced by a

null). Not only is it easier to work with ASCII characters,

but it makes things more consistent throughout the many ver-

sions of Kermit. When the packets are sent to the micro,

Kermit-CMS converts all data back to EBCDIC. The ASCII to

EBCDIC translation table can be found in the Appendix.

8. If a transfer becomes stuck, you can CONNECT back to the CMS

system and type a lot of carriage returns -- each one will

cause KERMIT-CMS to retransmit the current packet, until the

retransmission limit is reached, and you will be back at

"KERMIT-CMS>" command level.

9. Kermit-CMS supplies the micro and the user with numerous er-

ror messages. If the execution must be abnormally ter-

minated, an error packet is sent to the micro before

Kermit-CMS stops. The same message can be retrieved via the

STATUS command when Kermit-CMS returns and displays the

prompt. If Kermit-CMS aborted because the maximum amount of

retries was exceeded (20 on initialization packets and 5 on

others), the error message will display the most recent error

(i.e. the last NAK Kermit-CMS encountered). If execution

stops because the micro gave up, the error message will con-

vey that to the user, but it is the micro's responsibility to

pinpoint the error. The messages Kermit-CMS gives are as

follows:

"Bad send-packet size"

Sent when the micro attempts to set its receive buffer

size to a value that is less than 26 (the minimum that

Kermit-CMS will accept) or larger than 94, the maximum.

It will also occur if Kermit-CMS tries to send a packet

that is larger than the maximum specified.

"Bad message number"

This and the following messages flag inconsistencies in a

Kermit packet.

"Illegal packet type" -- This can be caused by sending server

commands.

"Unrecognized State"

"No SOH encountered"

"Bad Checksum"

"Bad character count"

"Micro sent a NAK"

"Lost a packet"

"Micro aborted"

The micro abnormally terminated the transfer.

"Illegal file name"

When receiving the name of the file from the micro,

Kermit-CMS expects it to be in the format

'filename.filetype'. If the filename, filetype, or dot

is missing, Kermit-CMS will reject (NAK) the packet.

Also, if either the filename or filetype exceeds eight

characters, it will be truncated.

IBM VM/CMS KERMIT Page 85

"Invalid lrecl"

Kermit-CMS will abort on any file-system error it en-

counters when reading from the file it is to send. It

can only send files with variable or fixed length record

formats, therefore, Wylbur Edit or Packed format files

will cause an error.

"Permanent I/O error"

This signifies a permanent I/O error that occured when

reading from an existing file. Execution is aborted im-

mediately.

"Disk is read-only"

Attempt to write on a read-only disk.

"Recfm conflict"

If a filename conflict arises, Kermit-CMS will append the

received file to the existing one, provided the record

formats of the two are the same. Otherwise, this error

will cause a halt of the execution.

"Disk is full"

Refers to any error regarding limitations on a user's

storage space. Most likely, it signifies that the

receiving disk is full, but the error can also mean that

the maximum number of files allowed has been reached, or

virtual storage capacity has been exceeded, and so on.

"Err allocating space"

Kermit-CMS keeps a table of all files it has sent to the

micro, allocating extra space if more than ten files are

sent at one time. If there is an error obtaining more

space, Kermit-CMS will abort with this error.

Work on VM/CMS Kermit continues. Planned future enhancements include:

1. 8-bit quoting, to allow binary files to pass through com-

munication front ends that insist on using the 8th bit for

parity.

2. Ability to act as a Kermit Server.

3. Ability to SET LINE, so that Kermit-CMS can be used as a

local Kermit, connecting to a remote host over another com-

munication port.

UNIX KERMIT Page 86

9. UNIX KERMIT

Authors: Bill Catchings, Bob Cattani, Chris Maio, Columbia University

with fixes and contributions from many others.

Documentation:

Walter Underwood, Ford Aerospace (Palo Alto, CA)

Version: (unnumbered)

Date: October 1983

A sample, working implementation of the Kermit "kernel" was written in the C language, and widely distributed in the Kermit Protocol Manual.

This kernel was intended merely to illustrate the protocol, and did not include a "user interface", nor some of the fancy features like server support, 8-bit quoting, file warning, timeouts, etc. Several sites have added the necessary trappings to make this a production version of Ker- mit, usually under the UNIX operating system.

The keyword style of user/program interaction favored by Kermit (program types prompt, user types command followed by operands, program types another prompt, etc) is contrary to the UNIX style, so UNIX implemen- tations have a style more familiar to UNIX users. C versions of Kermit are running successfully on VAX and PDP-11 UNIX systems, IBM 370-com- patible mainframes under Amdahl UTS, and the SUN Microsystems MC68000- based and other workstations.

UNIX filespecs are of the form

dir1/dir2/dir3/ ... /filename where the tokens delimited by slashes form a path name, and by conven- tion are each limited to 14 characters in length. The final token in a path is the actual file name. By convention, it is of the form name.type, but there is nothing special about the dot separating name and type; to UNIX it's just another character, and there may be many dots in a filename.

In the tradition of UNIX, here's the UNIX KERMIT "man page".

NAME kermit - file transfer, virtual terminal over tty link

SYNOPSIS kermit c[lbe] [line] [baud] [esc]

kermit r[ddilb] [line] [baud]

kermit s[ddilb] [line] [baud] file ...

DESCRIPTION Kermit provides reliable file transfer and primitive

virtual terminal communication between machines. It has

been implemented on many different computers, including

microprocessors (see below). The files transferred may

be arbitrary ASCII data (7-bit characters) and may be of

any length. The file transfer protocol uses small (96

character) checksummed packets, with ACK/NACK responses

and timeouts. Kermit currently uses a five second

timeout and ten retries.

UNIX KERMIT Page 87

The arguments to kermit are a set of flags (no spaces

between the flags), three optional args (which, if in-

cluded, must be in the same order as the flags which in-

dicate their presence), and, if this is a Send operation

a list of one or more files. (It is similar in some way

to the tar command structure).

Kermit has three modes, Connect, Send, and Receive. The

first is for a virtual terminal connection, the other

two for file transfer. These modes are specified by the

first flag, which should be c, s, or r, respectively.

Exactly one mode must be specified.

The d flag (debug) makes kermit a bit more verbose. The

states kermit goes through are printed along with other

traces of its operation. A second d flag will cause

kermit to give an even more detailed trace.

The i flag (image) allows slightly more efficient file

transfer between Unix machines. Normally (on Kermits

defined to run on Unix systems) newline is mapped to

CRLF on output, CR's are discarded on input, and bytes

are masked to 7 bits. If this is set, no mapping is

done on newlines, and all eight bits of each byte are

sent or received. This is the default for non-Unix ker-

mits.

The l flag (line) specifies the tty line that kermit

should use to communicate with the other machine. This

is specified as a regular filename, like "/dev/ttyh1".

If no l option is specified, standard input is used and

kermit assumes it is running on the remote host (ie. NOT

the machine to which your terminal is attached).

The b flag (baud) sets the baud rate on the line

specified by the l flag. No changes are made if the b

flag is not used. Legal speeds are: 110, 150, 300,

1200, 2400, 4800, 9600. Note that this version of ker-

mit supports this option on Unix systems only.

The e flag (escape) allows the user to set the first

character of the two character escape sequence for Con-

nect mode. When the escape character is typed, kermit

will hold it and wait for the next character. If the

next character is c or C, kermit will close the connec-

tion with the remote host. If the second character is

the same as the escape character, the escape character

itself is passed. Any character other than these two

results in a bell being sent to the user's terminal and

no characters passwd to the remote host. All other

typed characters are passed through unchanged. The

default escape character is '^'.

The file arguments are only meaningful to a Send kermit.

The Receiving kermit will attempt to store the file with

the same name that was used to send it. Unix kermits

UNIX KERMIT Page 88

normally convert outgoing file names to uppercase and

incoming ones to lower case (see the f flag). If a

filename contains a slash (/) all outgoing kermits will

strip off the leading part of the name through the last

slash.

EXAMPLE For this example we will assume two Unix machines. We

are logged onto "unixa" (the local machine), and want to

communicate with "unixb" (the remote machine). There is

a modem on "/dev/tty03".

We want to connect to "unixb", then transfer "file1" to

that machine.

We type:

kermit clb /dev/tty03 1200

Kermit answers:

Kermit: connected...

Now we dial the remote machine and connect the modem.

Anything typed on the terminal will be sent to the

remote machine and any output from that machine will be

displayed on our terminal. We hit RETURN, get a

"login:" prompt and login.

Now we need to start a kermit on the remote machine so

that we can send the file over. First we start up the

remote, (in this case receiving) kermit, then the local,

(sending) one. Remember that we are talking to unixb

right now.

We type:

kermit r

(there is now a Receive kermit on unixb)

We type ^ (the escape character) and then the letter c

to kill the local (Connecting) kermit: ^C

Kermit answers:

Kermit: disconnected.

We type:

kermit slb /dev/tty03 1200 file1

Kermit answers:

Sending file1 as FILE1

When the transmission is finished, kermit will type ei-

UNIX KERMIT Page 89

ther "Send complete", or "Send failed.", depending on

the success of the transfer. If we now wanted to trans-

fer a file from unixb (remote) to unixa (local), we

would use these commands:

kermit clb /dev/tty03 1200

(connected to unixb)

kermit s file9

^c (up-arrow c not control-c)

(talking to unixa again)

kermit rl /dev/tty03 1200

After all the transfers were done, we should connect

again, log off of unixb, kill the Connect kermit and

hang up the phone.

FEATURES Kermit can interact strangely with the tty driver. In

particular, a tty with "hangup on last close" set (stty

hup), will reset to 300 Baud between kermit commands.

It will also hang up a modem at that time. It is better

to run with "stty -hup", and use "stty 0" to explicitly

hang up the modem.

The KERMIT Protocol uses only printing ASCII characters,

Ctrl-A, and CRLF. Ctrl-S/Ctrl-Q flow control can be

used "underneath" the Kermit protocol (TANDEM line dis-

cipline on Berkeley Unix).

Since BREAK is not an ASCII character, kermit cannot

send a BREAK to the remote machine. On some systems, a

BREAK will be read as a NUL.

This kermit does have timeouts when run under Unix, so

the protocol is stable when communicating with "dumb"

kermits (that don't have timeouts).

DIAGNOSTICS cannot open device

The file named in the line argument did not exist or had

the wrong permissions.

bad line speed

The baud argument was not a legal speed.

Could not create file

A Receive kermit could not create the file being sent to

it.

nothing to connect to

A Connect kermit was started without a line argument.

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