Tim Mann's TRS-80 Pages

Business card from 1981

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Catweasel Floppy Read/Write Tools

The Catweasel floppy disk controller is an add-in card for the PC or Amiga, now no longer manufactured. It uses specialized hardware, not a standard floppy disk controller chip, and it can be programmed to read and write just about any disk format. Several versions have been made. The Catweasel MK4 is a PCI device (not PCIe), the older Catweasel MK3 has two connectors and plugs into either the PCI bus of a PC or the Zorro bus of an Amiga, the MK2 plugs only into an Amiga, and the original MK1 or Catweasel ISA plugs into the ISA bus of a PC. Although no longer made, the cards can sometimes be found used.

I wrote a set of programs for use with the Catweasel. My programs run on Linux, Windows 95, or MS-DOS and work with the Catweasel MK1, MK3, and MK4. They don't run on the Amiga -- sorry. Note: My Catweasel programs also do not run on Windows NT, 2000, XP, or 2003. I'm not sure if they run on Windows 98 or ME. The problem is that they talk directly to the hardware; they do not go through a device driver loaded into the operating system.

• cw2dmk can use a Catweasel to read several kinds of floppy disk, some of which ordinary PC controllers have trouble with, and write them out in the DMK disk image format used by xtrs and by David Keil's TRS-80 emulator. cw2dmk does not just read TRS-80 disks. It can make an exact image of any disk written using a Western Digital 177x/179x floppy disk controller, a PC-style NEC765-compatible controller, or a Digital Equipment Corporation RX02 controller. It does not support Amiga, Apple II, Atari or Commodore disks.
• dmk2cw uses a Catweasel to write any DMK image back to a real floppy disk. It can handle the same kinds of disks as cw2dmk.
• dmk2jv3 converts images from DMK format to the older JV3 format, for use with emulators and tools that do not support DMK. This program can be used to convert any DMK image that is representable in JV3 format, not just images written by cw2dmk. It does not require Catweasel hardware.
• jv2dmk converts images from JV1 or JV3 format to DMK. This program also does not require Catweasel hardware, but it is useful mainly to convert JV1 or JV3 images for subsequent writing to disk by dmk2cw. (The DMK images that jv2dmk produces will of course work with emulators that support DMK, but those emulators generally also support JV1 and JV3 directly.)

You can download the source code and executables for both Linux and MS-DOS below. The MS-DOS version also runs on Windows 95.

• I have not worked on the Catweasel Floppy Read/Write Tools for several years. Continuing development by several other folks to add new features and other improvements is now hosted at GitHub: https://github.com/qbarnes/cw2dmk.
• My last release was version 4.4 in 2010 (tar.gz format) (zip format). The package includes binaries for Linux and MS-DOS/Windows95.
• Also available are Win32 executables of jv2dmk and dmk2jv3 only, version 4.4 (zip format). These should run on modern 32- and 64-bit editions of Windows.
• Preview the documentation (version 4.4): cw2dmk - dmk2cw - dmk2jv3 - jv2dmk.
• The Catweasel was a product of Individual Computers, but is no longer available there.
• cw2dmk is partly based on the Catweasel drivers for Linux, which support Amiga and MS-DOS disks.
• The dmklib library reads and writes the DMK image format.

Currently, DMK and JV3 disk images are useful mostly with TRS-80 emulators, but the ability to read disks with cw2dmk and write out copies with dmk2cw also provides a nice way of archiving disks from old machines and making physical copies when needed. The dmklib project noted above may lead to still more applications.