ZoomFloppy Manual
v2.0 – Sept 24, 2011
This manual describes how to install and use the ZoomFloppy USB floppy adapter. The
ZoomFloppy connects your Commodore 1541/1571/1581 and CBM IEEE-488 drives (and even
serial printers) to a Windows, Mac, or Linux computer. This allows you to read and write files or
entire disk images from the original media. Unprotected disks can be read to or written from D64
image files, say for use with emulators. Protected disks can be read to or written from NIB or
G64 files, provided you have a 1571 drive or install a parallel cable in your 1541 drive.
Introduction to the ZoomFloppy
At a minimum, the ZoomFloppy must be connected to one or more floppy drives via the IEC
serial port (6-pin DIN) and to a computer via USB. It is powered over USB, so no external
supply is needed. This configuration gives basic access to read and write disks. OpenCBM
provides some faster serial transfer routines and defaults to auto-selecting the best one for your
For higher performance and to copy protected disks, you may want to install a parallel cable in
your drive (not included). This cable was originally produced for Speed DOS and Burst Nibbler.
It is attached to one of the VIA chips (1541) or CIA chip (1571), either by removing the chip and
installing a socket or by soldering. It gives an 8-bit parallel channel to transfer raw GCR bytes at
a higher speed. These cables usually add a DB15 female connector to the drive, also known as a
game port on the PC. With a 1571 drive, high-speed serial nibbling can be used and the parallel
cable isn’t necessary.
Once this is installed, the drive can be connected to the ZoomFloppy in one of three ways. If you
already have a C64 cartridge plug to DB15-M cable, it attaches to the card edge at the bottom of
the ZoomFloppy. Be sure to note which side is up since the connector fits both ways. If you
don’t, it’s usually cheaper and easier to get a DB15-F to DB15-M cable. This connects to the
DB15 plug on the left side of the ZoomFloppy. Finally, if you’re building your own cable, you
can solder a 2x8 header onto connector X4.
The firmware now supports IEEE-488 floppy drives, which were produced for the PET. Either
the large GPIB plug can be soldered onto the board on the right or a 2x12 header can be added at
Finally, a 2x20 expansion header can be added at X5. This maps all signals from the
microcontroller for debugging or some unknown future use.
Optional case
While it works just fine as a bare board, the ZoomFloppy was designed to be placed in a case,
Hammond part number 1591XXTSBK. This case is available from many suppliers, such as Digikey. You’ll have to cut at least one side of the case to allow for the connectors.
The case dimensions in inches are 4.853 wide x 3.278 long x 2.2 deep (without lid). More info
on the exact dimensions can be found on the above pages.
Windows installation (2000, XP, Vista, 7)
This distribution provides Windows binaries for OpenCBM, supporting the ZoomFloppy USB
interface. The code has not been customized, so you can also install from stock OpenCBM
source code, although that procedure is a bit more complicated. It is expected that future builds
will be available directly from the OpenCBM project.
You should have gotten the installer and this manual from the following site. Do not install the
0.4.x series of binary installers from the OpenCBM website as they do not support the
Below are the directions for installing OpenCBM for ZoomFloppy on Windows. Mac OS X and
Linux also work with the ZoomFloppy, but OpenCBM installation for them is not described
Even if you have previously installed OpenCBM, you’ll need to install this newer version in
order to get ZoomFloppy support. Do not install an older copy of OpenCBM, such as 0.4.x, since
it does not support the ZoomFloppy.
A. Run the file "install.bat" by double-clicking on it
This installs the OpenCBM package in C:\opencbm\bin and the Windows system dir. If you want
to install to a different dir, edit the install.bat file to change this path. You can run this script
multiple times without uninstalling first. To uninstall, just run
"instcbm --remove".
To use the OpenCBM utilities, you can install a separate GUI such as GUI4OPENCBM or
CBMXfer (see below for links to these). The command line utilities can be used directly from
the shell by adding C:\opencbm\bin to your PATH environment variable.
B. Plug in the ZoomFloppy via USB and install the Windows driver
Once you plug in the ZoomFloppy, you'll see a standard device driver installation prompt. We'll
be installing a driver extracted from this zip file, located under the "windrv" folder. You do not
need to reboot after installing the drivers.
After plugging in the ZoomFloppy, you’ll see the following dialog. This example uses Windows
XP – other versions vary but the basic steps are the same. See the next section for Windows 7.
1. Select "No, not this time" when prompted by the New Hardware Wizard
2. Click Next
3. Select "Install from a list or specific location"
4. Click Next
5. Browse to the "windrv" folder extracted from the OpenCBM zip file
6. Click "OK"
7. Verify your screen looks like the above and click Next.
The drivers are now being installed and you can click Finish when done.
C. Update your ZoomFloppy’s firmware
New features are added regularly to the ZoomFloppy, so you’ll need to update it as well. Even if
you just purchased it, you can always give this a try. If your device is up-to-date, the updater will
detect this and not change anything.
Just double-click on the “firmware-update.bat” file in the installation folder or see the section
below on “Updating your firmware” for more info.
D. Unplug the ZoomFloppy from USB and connect it to your floppy drive
1. Plug in your drive's power cord if it's not connected already.
2. Plug an IEC serial cable (round, 6-pin plug) into both the ZoomFloppy and your drive.
3. Optional: if you have installed a drive parallel cable, connect it also. The ZoomFloppy
has three plugs for parallel devices: the 15-pin D-SUB connector, 16-pin rectangular
header (Z3), and the card edge connector at the bottom (similar to the C64 cartridge port).
E. Plug the ZoomFloppy back into USB
The LED on it should come on but you shouldn't get a driver installation prompt this time. If you
do, something went wrong installing the drivers and you should repeat step B, above, or see the
troubleshooting section below.
F. Turn on your floppy drive(s)
G. Test that the ZoomFloppy is working
Run the file “runtest.bat” by double-click on it. This will run the command “cbmctrl detect”,
which will print out any IEC devices that are connected and powered on.
8: 1540 or 1541
If you see something like this, you’re done! If not, check that the floppy drive is plugged in and
powered on. If there are still problems, see the troubleshooting section below.
Windows 7 driver Installation
This works mostly the same way as the Windows XP install above. Here are the step-by-step
instructions for installing the drivers on Windows 7.
First, plug in the ZoomFloppy via USB. You may see a brief message about looking for drivers
and no driver found in your status tray at the lower right. Go to your Start button and click on the
search box. Type in “device manager” and click on the first entry.
The device manager will open and you’ll see a ZoomFloppy (xum1541) device with a yellow
exclamation mark. This means no drivers are installed yet.
Click on the xum1541 item in the list and select “Update Driver Software…” from the Action
menu at the top.
Select the “Browse my computer for driver software” button.
Now, click the “Browse…” button and navigate to the folder called “windrv” in your
ZoomFloppy installer folder. Then click “Next” at the bottom right.
Windows will complain because our device driver was not reviewed and signed by them. This is
ok, as long as you got the ZoomFloppy installer from a trusted source. Select “Install this driver
software anyway”.
The installation will continue for a little while. If it succeeds, click “Close” to exit the installer.
The device manager should now show the ZoomFloppy device with a little USB plug icon next
to it. If so, you’re done!
If there is still a yellow exclamation mark as at the beginning, please try again or see the
Troubleshooting section below.
Updating your firmware
If you’re installing this software as an update, you’ll also need to update the firmware in your
ZoomFloppy. This is a simple process and has seatbelts to make sure things go properly.
For Windows users, just double-click on the “firmware-update.bat” file in the ZoomFloppy
installation folder. It should print the following messages:
updating firmware...
update completed ok!
The update tool itself can be run from the command line by Mac and Linux users. Usage:
xum1541cfg update xum1541-ZOOMFLOPPY.hex
Do not unplug the ZoomFloppy from USB while it is updating. You should turn off all
connected drives before running the update utility. If you have any problems, please report them
to the mailing lists in the Support section.
Mac OS X and Linux installation
Both of these operating systems are supported by the ZoomFloppy, but you’ll have to install
from source code. For the Mac, installation is easiest via Mac Ports and these instructions:
For Linux, this discussion thread may be useful.
Using OpenCBM and related software
Here are some documents on how to use OpenCBM. All the commands are supported by the
ZoomFloppy. Do not download the binaries for OpenCBM 0.4.x as they do not support the
There are several GUIs for OpenCBM.
You can get nibtools from the C64 Preservation website.
Adding a parallel port to your drive
For copying protected software with nibtools or the highest speed transfers, adding a parallel port
to your 1541 drive is a must. These cables, originally designed for SpeedDOS and Burst Nibbler,
connect the VIA or CIA chip in your 1541 or 1571 drive to a 15-pin D-SUB female connector,
aka game port. Note that the 1571 supports serial nibbling, so a parallel cable is not necessary.
The best way to attach the cable is the solderless approach. You remove the VIA in your drive,
plug in a socket, and then plug the VIA into the socket. The D-SUB port is then attached to the
case or routed out the back. Peter Schepers sells these cables (see section “Disk Drive Parallel
Ports & Cables”, solderless options).
Then you need a cable to connect the drive to the ZoomFloppy. The easiest route is to get a 15pin D-SUB male-to-female cable. If you want to use your new parallel port with a C64 also, you
should get the “C64 user port parallel cable”, also available from the above site. It plugs into the
card edge connector on the ZoomFloppy.
Here are some steps to help you solve common problems. The ZoomFloppy is pretty reliable and
simple to use, so there aren’t many things that can go wrong. If you suspect a hardware problem,
get help on the zoomfloppy-users mailing list or contact RETRO Innovations to make a return.
ZoomFloppy LED does
USB port inactive
not turn on when plugged
into the computer via USB
Bad USB cable
Firmware not installed or
has been erased
“cbmctrl detect” returns an PC’s drivers not installed
error (“no xum1541
or improperly installed
device found”)
ZoomFloppy not plugged
into USB
“cbmctrl detect” returns
nothing (no error)
Drive not connected via
IEC cable or not powered
Things to try
Plug the ZoomFloppy into
another port or computer. If
using a USB hub, try using a
port on the PC instead.
Try another cable
Reinstall the ZoomFloppy
firmware. Note this only
needs to be done if the
firmware was erased or if
Reinstall the drivers
Check the USB connection
and try again. Unplug the
USB cable and plug it in
again to reset the board.
Unplug ZoomFloppy from
USB to power it off. Then,
connect drive cable, plug in
ZoomFloppy, power on drive
If you are still having problems, there are mailing lists to contact. If you completed the
installation and drive detection succeeds as described above, try the OpenCBM mailing list for
general questions about using the software:
If the installation failed and you tried the troubleshooting steps, you can report your problem to
the ZoomFloppy users list. RETRO Innovations and the xum1541 developers monitor this list
and can handle hardware problems or other similar issues.
Do not plug or unplug any cables to the floppy drive when the drive is powered on or the
ZoomFloppy is connected to a PC via USB. When the ZoomFloppy is plugged into USB, it is
powered on and could zap your drive if you connect or remove a floppy drive. This is also the
same way you should treat floppy drives attached to your Commodore computers.
Do not attach more than 4 floppy drives to a single ZoomFloppy. If you need more drives, get
another ZoomFloppy. The OpenCBM software allows you to use more than one ZoomFloppy at
the same time (subject to PC performance limitations).
Do not connect more than one drive to the ZoomFloppy parallel ports. While there are multiple
connectors, only one should be used at a time.
When accessing floppy drives, all devices connected to the IEC bus must be turned on. Even if
you are only going to use one drive, for example, all other connected drives must also be turned
on. Unpowered IEC devices may interfere with proper operation of other drives.
Be careful of static electricity discharge when plugging/unplugging any electronic equipment.
Consider getting a case for your ZoomFloppy board if you are concerned about the environment
you will be using it in.
Proper power-on sequence
We have tested leaving the ZoomFloppy connected to powered-on drives for days with no
problems, even though it was not connected via USB. You also can leave the ZoomFloppy
plugged into USB with the drive(s) off with no problems. But while the ZoomFloppy is designed
to be robust, you can avoid unnecessary wear by following these instructions for starting up and
shutting it down.
Start with drive off and ZoomFloppy unplugged from the PC’s USB
Plug in all cable(s) between ZoomFloppy and drive
Plug in ZoomFloppy via USB
Turn on drive power switch(es)
Turn off the equipment via the same sequence in reverse, at least doing steps 4 and 3. You don't
need to unplug the floppy drive from ZoomFloppy while not in use. The 15x1 drives with an
internal power supply tend to get hot if left on for a long time, so you may want to power them
off when not in use.
Nate Lawson designed the ZoomFloppy over several years. He built the prototype boards
and wrote the firmware, OpenCBM plugin, nibtools mods, and this manual.
Jim Brain at RETRO Innovations did the PCB design, manufacturing, and hardware sales
and support.
Wolfgang Moser provided design advice and lots of debugging assistance with his
complex drive setup.
Thomas Winkler implemented the IEEE-488 support.
Arnd Menge implemented the 1571 serial nibbling support.
Christian Vogelsgang did the Mac port and was an early tester.
Spiro Trikaliotis, Joe Forster, and Thomas Kindler all helped review changes and provide
advice, in addition to other code they’ve written.
Peter Rittwage continues to update nibtools to support reading/writing protected disks.
Original code for mnib was by Markus Brenner.
Dean Camera provided the very useful LUFA AVR USB library