Since CP/M was written to run on the Intel 8080 CPU (and, by extention, the Zilog Z80 CPU), Apple CP/M implies installing some sort of accessory card which provides this CPU.
With this CPU card and supporting software, the Apple computer supplies the keyboard, display, mass storage and (in most cases) the working RAM to become a real Z80-based computer running the most popular 8-bit operating system ever devised.
There are numerous SoftCard clones and workalikes. Most are ``no-name'' CP/M cards, but a few with names are the Applied Engineering Z80+ and the Advanced Logic Systems' (ALS) Z-Engine.
Applied Engineering's Z80c and Z-RAM Ultra III allowed the Apple //c (not the //c+) to run CP/M. These effectively made the //c look to software like an Apple //e with AE's Z80+ installed in slot 4.
A special version of the SoftCard, called the Premium SoftCard //e was designed to be installed in the AUX: slot of the Apple //e. It held its own DRAM for CP/M and communicated with a small 6502 I/O processor program that ran on the native Apple CPU. A later version of the SoftCard, called the SoftCard II, ran in a standard Apple ][ peripheral slot and had 64K of DRAM on it, but the author of this page knows little else about it. There was also a version of the MicroSoft SoftCard for the Apple ]I[.
A much more sophisticated approach was taken by Personal Computer Products, Inc. (PCPI) with the PCPI AppliCard. Click on the highlighted name to read more about it.
The Seven League Systems' CardZ180 is an HD64180-based card whose design was inspired by that of the AppliCard.
A hybrid approach was taken by ALS with their ``The CP/M Card'', which was co-developed with Digital Research, Inc. (DRI), the maker of CP/M. ``The CP/M Card'' was designed to run DRI's new CP/M Plus (v3.0) operating system that required 128K of RAM instead of just 64K. To do this, ``The CP/M Card'' used the Apple's main memory for the extra RAM required by the sophisticated OS functions, while using its own 64K of DRAM for user programs and the tiny portion of the OS that had to reside in that space.
More to come...
© 1995 John D. Baker,
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