Autopsy:

from MOS6502 Homepage:

The idea of running the multitude of CP/M software on your Commodore surely was one of the drivers for people to invest in the C128. But what about that obscure CP/M cartridge, containing of course the Z80 CPU (running at 3MHz), that Commodore released for the C64 in 1983?  Did this introduce CP/M for the classic Commodore computer?

At least in theory, the cartridge would open up the world of CP/M to the C64 user, but 1541 disk drive incompatibilities made it next to impossible to run CP/M software on the home computer.  A disk of, let’s say an Apple (CP/M) would simply not run and only produce a “Bad Track” or “Bad Sector” error.

Commodore quickly stopped manufacturing these cartridges and Commodore users had to wait till the C128 before they could really start playing around with CP/M So was the CP/M cartridge a complete waste?  Surely there would be some “proprietary” Commodore CP/M software for the C64? The answers are “no” and… “no”.

This may seem a bit contradictory but there was one neat little trick that you could do to actually run the CP/M programs out there and it didn’t involve the incompatible disk drive: you had to utilize the user port to transfer CP/M software from another machine… talk about some workaround!

Download: Cartridge Schematic & Manual (1590)

source: mos6502.com