Commodore Plus/4 and C16:
Hardware and Advanced Basic
Programming.
Version 1.01
by Janne Peräaho & Anders Persson
●
●
●
●
Introduction
Slow and Fast
Restore key
Window Command
2
2
2
2
● Screen Codes / TED Text modes
● Default Character Set
● Your own Character Set
3
4
6
● Escape codes
6
●
●
●
●
7
7
7
8
ROM
How to access rom programs?
Kernal jump table
3-plus-1
AUTHORS
Janne Peräaho
E-mail: [email protected]
Pyrytie 11 A 9
90630 Oulu
Finland
Anders Persson
http://listen.to/boray
Thanks to Brian Flood for the Plus/4 and to Janne for the cooperation.
ALL DOCUMENTS
This document is part of a document package for Plus/4, C16 and C116 users. The
documents included are:
●
●
●
●
"basic35.pdf",
"short35.pdf",
"advanced.pdf",
"tedmon.pdf",
Janne's original Basic 3.5 manual (more or less)
a Basic Quick Guide.
This document - The Hardware and Advanced Basic programming.
a short description of the built in machine language monitor.
REFERENCES
Commodore Vic-20 and C64 programmers reference manual, Talking to TED by Levente
Harsfalvi, Commodore plus/4 and c16 memory map.
1
INTRODUCTION
The TED chip is the graphics and sound chip of these computers. For a good description
and a memory map of it, read this article:
http://www.canberra.edu.au/~scott/C=Hacking/C-Hacking12/gfx.html
Complete Memory maps of the Plus4/C16:
http://www.funet.fi/pub/cbm/maps/C16.MemoryMap
http://plus4.emucamp.com/tools/rommap/index.php
SLOW/FAST
These computers run at two processor speeds (~1.7MHz) and a slow (~0.9MHz) at the same
time. Well, not at the same time, but it constantly switches between the fast and slow
processor speeds. It's slow whenever the raster beam is on the visible screen, and
fast otherwise. The resulting speed is about 1.1MHz for NTSC and 1.2MHz for PAL. If
you switch off the display, it will run on the fast speed all the time. You can use
this from Basic, just as the FAST and SLOW commands on the C128:
POKE 65286,0 (the screen goes blank) and back: POKE 65286,27
RESTORE KEY?
If you have used a vic20/c64/c128, then you might wonder where the "restore" key is?
But there is none! To perform something like it, hold down run/stop and press the
reset button. This enters the monitor. Type X and hit return to return to basic. The
basic program remains in memory.
I don't know about you, but I find that procedure a little akward. So why not make
your own restore key instead? When programming Basic, the most common reason to use
the vic20/c64/c128s restore key is to restore the colors, sound and graphics mode to
the default. But this can be done with SYS commands! So let's define a function key:
KEY 1,"{clr home}SYS65418:SYS65409:SYS65412"+CHR$(13)
Then to perform the equavilence to the c64's runstop-restore, first press run/stop to
break the program (if it's running), release and then press F1. How nice! If you like,
you can put LIST in there too, because that is probably the command you most often
like to do after the restore:
KEY 1,"{clr home}SYS65418:SYS65409:SYS65412:LIST"+CHR$(13)
If you like, you can also put this line in the program you are working on so that you
don't need to type it in every time you turn on the computer.
The sys commands used are RESTOR, CINT and IOINIT from the Kernal.
Another little tip (if you don't have made your own restore key) and you just want to
get out of a basic graphics mode without having to type GRAPHIC 0. Then just press any
key followed by return. The basic will then answer with ?SYNTAX ERROR and go to
GRAPHIC 0 by itself to display the error message.
WINDOW COMMAND
The C128 has a WINDOW basic command to set the output window to just a part of the
screen. The C16/Plus4 has the same feature but no specific command for it. You can do
it with Esc codes (Look at page 6 for the whole list) or with pokes. The Esc codes to
use are Esc-T to set top of window, Esc-B to set bottom and Esc-N for the full screen
(and clearing it). The pokes to use are 2021 (Screen bottom), 2022 (Screen top), 2023
(Screen left) and 2024 (Screen right). Also, the CHAR command restores the window to
the whole screen without clearing it (compared to Esc-N that also clears the screen).
If you only use the pokes, then you need to follow up with a PRINT"{home}"; or the
output could start outside of the new window. So for something like the C128's window
command, you could use this line (which probably is the shortest way of doing it):
CHAR, X1,Y1,CHR$(27)+"T":POKE2024,X2:POKE2021,Y2
Where (X1,Y1) is the top position and (X2,Y2) is the bottom position.
2
SCREEN CODES (TED text modes)
The Screen memory starts at 3072 by default.
The color/attribute memory starts at 2048 by default.
Normal Text (the default) (8x8 pixle characters)
● Screen memory: Bits 0-6 is one of 128 characters and bit 7 is reverse on/off.
● Color memory: Bits 0-3: Color, Bits 4-6: luminance, Bit 7: Flash on/off
Examples: Poke 3072,1 (puts an A at top left screen position)
Poke 3073,2+128 (puts a reverted B beside it)
Poke 2048,128+2+5*16 (makes the A light red and blinking)
256 Char display (8x8 pixle characters)
Turn on with Poke 65287,peek(65287) OR 128
● Screen memory: Bits 0-7 is one of 256 characters.
● Color memory: Bits 0-3: Color, Bits 4-6: luminance, Bit 7: Flash on/off
Multi Color (4x8 pixle characters)
With multicolor (lo-res) turned on, you have to design your own characters where
every byte is built of four bit pairs = 4 pixles. Every pixle is in memory two
bits, so there are four different combinations, 00, 01, 10, and 11 which each
represent a different color.
Turn on with poke 65287,peek(65287)or16
● Screen memory: Bits 0-7 is one of 256 characters.
● Color memory:
Bit 3: Multicolor on/off. (Both multicolor (4x8) characters and
hires (8x8) characters can be displayed on the same screen.)
Bits 0-2 Color and
bits 4-6 luminance for the "11"-pixles in the charterset.
For the rest of the combinations:
"00"=background (color 0) (address 65301 bits 0-3 color and 4-6 luminance),
"01"=color 3 (address 65302) and "10"=(address 65303).
Extended Color (8x8 pixle characters)
(This means you can have different background colors to different hires
characters on the same screen)
Turn on with Poke 65286, peek(65286)or64
● Screen memory:
Bits 0-5 is one of 64 characters.
Bits 6-7 is background color for the character:
"00"= normal background (color 0) (65301 bits 0-3 color and 4-6 luminance),
"01"= color 3 (65302), "10"= (65303) and "11"= (65304).
● Color memory:
Bit 3: Extended color on/off.
Bits 0-2 Foreground Color and
bits 4-6 luminance.
(There are also two bitmap modes: Hires (320x200) and Multicolor (160x200). These
are easiest used from basic with the GRAPHIC command. The only text modes that
works with "split screen" seems to be Normal Text and 256 char display.)
3
DEFAULT CHARACTER SET:
SET 1 SET 2 POKE SET 1 SET 2 POKE SET 1 SET 2 POKE
•
@
0
U
21
42
u "
A
a
1
V
v
22
B
b
2
W
w
23
44
C
c
3
X
x
24
45
D
d
4
Y
Y
25
46
E
e
5
Z
z
26
I
47
F
f
6
[(A)
a
27
!i1
48
G
9
7
t(O) 6
28
1
49
H
h
8
J(A)
A
29
2
50
9
t
30
3
51
+-
31
4
52
11
32
5
53
12
33
6
54
J
K
10
k
L
+
43
M
m
13
..
34
7
55
N
n
14
#
35
8
56
0
0
15
$
36
9
57
P
P
16-
%
37
58
Q
q
17
&
38
59
R
r
18
39
<::
60
S
5
19
40
=
61
T
t
20
41
:>
62
4
le
I
SET 1 SET 2 POKE SET 1 SET 2 POKE SET 1 SET 2 POKE
?
106 _
T
63
84
[0
B
64
~
A
65
IT]
B
66
El
C
67
D
68
E
69
F
70
G
71
H
72
EJ
EJ
D
[0
[]
[]
[J
EJ
0
[SJ
73
Cd
~
IQ] u
~
[]
[!]
EB
IJ
DJ
85
V
86 a.'
W
87
[9
109
X
88
5J
110
Y
89
~ t
111
Z
90
Cd
112
A
91
113
b
92
A
93
E9
Ea
8J
D
~
~ ~
11'
94
74
K
75
L
76
IJ
97
M
77
~
98
0
0
0
N
78
0
79
P
80
[IJ
Q
81
D
R
82
~
S
83
•0
114
115
116
117
118
U
U
119
99
~
121
100
D
101
~
~
~
~
~
102
103
104
~'_L105
5
108
[]
[J
95
96
~
~
107
U
J
0
0
0
0
CB
C.
le
120
./
122
123
124
125
126
127
,
YOUR OWN CHARACTER SET
First you have to tell that characters should be fetch from RAM. This
is done by clearing the second bit of the TED register number 65298 ($FF12):
poke 65298, peek (65298) and 251
Then you must select a "memory page" where your character set is stored.
Each page is 1024 bytes long, so on the C16 there are 16 possible locations:
Page
Page
Page
...
Page
Page
0: characterset starts at memory address 0
1: characterset starts at memory address 1024
2: characterset starts at memory address 2048
14: characterset starts at memory address 14336
15: characterset starts at memory address 15360
(On the Plus4 there are more pages, probably 64)
Bits 2-7 of the TED register number 65299 ($FF13) determine, which page
should be used. To select a page do as follows:
poke 65299, (peek (65299) and 3) or (page * 4)
Another way of doing the same thing is to take the first byte in the address (as
long as one of the pages are used). For example, page 15's address is 15360. The
hex number for this is $3c00. So you can just poke 65299, dec(“3c”).
When using Basic one should protect the character set so, that Basic's program
text does not overwrite your character data. This can be done by setting the
upper limit for the Basic text, i.e. the highest address Basic is alloved to
use. To do that, use memory addresses 55 ($37) and 56 ($38). 55 is the lower
half of the 16 bit address and 56 is the upper half.
To switch back to ROM character set, just set the 2nd bit of the 65298 and set
the page back to page 52:
poke 65298, peek (65298) or 4 : poke 65299,208
ESCAPE CODES
Cancel quote and insert mode
Cancel started Esc code
ESC O
ESC X
Erase to end of current line
Erase to start of current line
ESC Q
ESC P
Move to start of current line
Move to end of current line
ESC J
ESC K
Enable auto-insert mode
Disable auto insert mode
ESC A
ESC C
Delete current line
Insert line
ESC D
ESC I
Enable scrolling
Disable scrolling
Scroll up
Scroll down
ESC
ESC
ESC
ESC
L
M
V
W
Set
Set
Set
Set
ESC
ESC
ESC
ESC
B
T
R
N
bottom
top of
window
window
of screen window
screen window
to full screen minus 1 and clear
to full screen and clear screen
Example: Press Esc followed by A for auto insert mode, or PRINT CHR$(27);"W" to scroll
the screen down from basic.
6
ROM
The C-16's ROM consists of three main parts: BASIC, TEDMON and KERNAL. BASIC is a
Basic interpreter, which can run Basic programs stored in RAM. TEDMON is a
machine language monitor for manipulating memory and writing short machine
language programs. KERNAL is not a single runnable program, but a collection of
system routines arranged as a Jump Table. The Plus/4 also includes a built in
software package called "3-plus-1" that includes word processing, spread sheet,
business graphics and a database.
HOW TO ACCESS ROM PROGRAMS?
BASIC is the primary user interface and it starts automatically when
power is turned on. The secondary user interface is TEDMON, which can be
entered by holding down the Reset button when turning the computer on.
You can also activate TEDMON from BASIC and vice versa. See Basic's MONITOR
command and TEDMON's X command.
The KERNAL is used by the Basic interpreter and other programs. Using KERNAL
routines requires a little machine language knowledge since it is required to use
processor registers for exchanging information between a KERNAL routine and the
routine caller. It is however possible to call KERNAL routines directly from Basic
with the use of the SYS command and the following memory positions: 2034=A,
2035=X, 2036=Y. For example, POKE 2034,23 and the accumulator will contain the
value 23 when the SYS command is started.
To call a KERNAL routine do as follows:
1. Set parameters.
2. Call KERNAL routine using JSR command (or SYS from Basic).
3. Handle any return error.
Note, that some routines need to be initialized with other routines before they
can be used. For example, using the SAVE routine requires initialization with
the SETLFS and SETNAM routines.
See the "KERNAL Jump Table" below for more information on available KERNAL
routines.
Basic example:
10 SYS DEC("FFE4") : REM "GETIN"
20 A=PEEK(2034) : IF A=0 THEN 10
30 A$ = CHR$(A)
Equals to:
10 GETKEY A$
KERNAL JUMP TABLE
Seems to be exactly the same as for the C64. Please consult the C64 programmer's
reference manual for parameters. Available on http://www.funet.fi/pub/cbm/c64/manuals/
Routine
Address
Function
CINT
IOINIT
RAMTAS
RESTOR
VECTOR
SETMSG
SECOND
TKSA
MEMTOP
MEMBOT
SCNKEY
SETTMO
ACPTR
CIoUT
UNTLK
UNLSN
$FF81
$FF84
$FF87
$FF8A
$FF8D
$FF90
$FF93
$FF96
$FF99
$FF9C
$FF9F
$FFA2
$FFA5
$FFA8
$FFAB
$FFAE
Initializes screen editor.
Initializes I/O devices.
Tests RAM.
Restores vectors to initial state.
Changes vectors for user.
Controls O.S. messages.
Sends SA after LISTEN.
Sends SA after TALK.
Sets/reads top of memory.
Sets/reads bottom of memory.
Scans keyboard.
Sets timeout in DMA disk.
Handshakes serial bus or DMA disk byte in.
Handshakes serial bus or DMA disk byte out.
Sends UNTALK out serial bus or DMA disk.
Sends UNLISTEN out serial bus or DMA disk.
7
LISTN
TALK
READSS
SETLFS
SETNAM
OPEN
CLOSE
CHKIN
CHOUT
CLRCH
SETLFS
CHRIN
CHROUT
LOAD
SAVE
SETTIM
RDTIM
STOP
GETIN
CLALL
UDTIM
SCRORG
PLOT
IOBASE
$FFB1
$FFB4
$FFB7
$EF8A
$FFBD
$FFC0
$FFC3
$FFC6
$FEC9
$FECC
$FFBA
$FFCF
$FFD2
$FFD5
$FFD8
$FFDB
$FFDE
$FFE1
$FFE4
$FFE7
$FFEA
$FFED
$FFF0
$FFF3
Sends LISTEN out serial bus or DMA disk.
Sends TALK out serial bus or DMA disk.
Returns I/O STATUS byte.
Sets LA, FA, SA.
Sets file name.
Opens logical file.
Closes logical file.
Opens channel in.
Opens channel out.
Closes I/O channels.
Sets logical file number and command of device.
Inputs one character from keyboard.
Outputs one character to screen.
Loads/verifies memory from device.
Saves memory area to device.
Sets internal clock.
Reads internal clock.
Scans STOP key.
Gets one character from keyboard queue.
Closes all files.
Increments clock.
Screen org.
Gets/sets cursor position.
Returns location of start of I/O.
3-PLUS-1
The extra software package built into the Plus/4 is started by pressing the F1 key
followed by return. The word processor is started by default. For the other parts,
hold down Commodore and press C, then type TC (followed by return) for
Spreadsheet, TF for file manager (database) or TW to jump back to the word
processor.
THE WORD PROCESSOR
Here are the word processor's commands: Press Commodore+C followed by
CA
CP
DF
IB
LF
RE
SR
-
Directory
Clear pointers
Delete file
Insert block
Load file
Search and replace
Search
CB
CT
DL
ID
MF
SF
*P
-
Create block
Clear tabs
Delete line of text
Format disk
Merge file
Save file
Prind doc in memory
CM
DB
EP
IL
PR
SP
-
Clear memory
Delete block
Erase pointer
insert text line
Print document
Set pointer
Keys:
CLR - move to bottom
Ctrl-0 reverse off
C=-R - move to col 41
C=-@ - Undo return
Return - Terminate line
Ctrl-= - Set a Tab
Del - Backspace
C=-L move to left margin
Home - Home
Sh-Return - to left marg.
Ctrl-9 - reverse (formatting)
C=-C - Command mode
C=-Q - Repeat prev keystroke
Instert - Instert
Shift-= - Tab key
Document formatting: The following keywords can be embedded in the text. They are
written in reverse video and typed in lowercase. ":" is used to separate multiple
instructions on the same line and ";" is used to terminate the instruction. For
example papersize50;
asc
center
justify
linkfile
lmarg
nextpage
nojustify
nowrap
no#page
other
pagelen
pagepause
papersize
pause
rmarg
set#pg
#page
wrapon
Send ascii character to the printer.
Center this line.
Justify text
Link documents at print time (with PR). Example: linkfile "opa";
Set left marginal. Example: lmarg9; (default is 0)
Page break
Turn off justify (default)
Turns of word wrap (for spreadsheets)
Deactivates #page command
Used with non-Commodore printers (normal Ascii-printers).
Sets page length. (Default is 60).
Pause printing after every page.
Changes size of the paper from default 66. Use together with pagelen.
Pause printing until you press return.
Set right margin (default is 77).
Set page number. Used together with #page.
Print page number at the bottom of the page.
Turn word wrap on (default).
8
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