Project catweasel

Revision as of 23:55, 5 August 2010 by Ezrec (Talk) (Interfacing with Linux)

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CatWeasel Mk2 Floppy Controller

The CatWeasel Mk2 Floppy Controller is available from [Individual Computers], and is readily available on the Ebay and Resale markets.


The CatWeasel Mk2 was designed to work only on the Amiga 1200 (via the 'clockport' internal expansion adapter, or the Amiga 4000's IDE interface (which, due to a feature of its design, allowed extra hidden IDE control ports to be available as a side-band).

0x1f0-0x1f7 => Pass through to IDE devices 0x3f6 => Pass through to IDE devices 0x3f0-0x3f5 => Controls the CatWeasel Mk2

Interfacing with Linux

Unfortunately, we can't just plug the CastWeasel Mk2 into an IDE cable and go. The PATA IDE ports on the 'upper' range of the the PATA interface are trimmed to only port 0x3f6. Ports 0x3f0-0x3f5 (needed for the CatWeasel interface) are not available.

However, we can use the CatWeasel Mk2 via the IDE port on almost any x86 Linux machine with native PATA IDE ports, with a simple IDE cable modification. By swapping the IDE_CS0 (pin 37) and IDE_CS1 (pin 38) lines, we can make a dedicated PATA IDE cable to talk to the CatWeasel Mk2.

  1. Build a 40-pin IDE cable with a twist on the next to last two lines (37 and 38).
    • This swaps the chip selects (IDE_CS0 and IDE_CS1) for the upper and lower set of registers. In this way, ports 0x1f0-0x1f7 will now actually be sent as ports 0x3f0-0x3f7.
  2. Connect the 'Weasel' cable from a PATA motherboard port to the CatWeasel Mk2.
    • NOTE: A USB to IDE adapter will *not* work. You must use a motherboard PATA port!
    • NOTE: The 'index' pin is may not removed on some the CatWeasel Mk2 IDE connectors. Please be careful when removing it.
  3. Apply the following software patches as needed:
    • [[1]] Mk2 via IDE support for Tim Mann's [cw2dmk] tool.