Through the early '80s CP/M was one of the more popular systems, especially for business applications. One advantage it had was that it was expected to run on all manner of systems, so software generally had the ability to be configured for various terminals and other hardware.
For systems already based on the Z80, such as the TRS-80 Model I/III/IV and the ZX Spectrum, this sometimes required a hardware modification to tweak the address decoding; you could do this yourself or third-party vendors often offered the modification. It wasnāt unusual for later models in the series (TRS-80 Model 4, Spectrum 3+) to be changed to directly offer CP/M support.
For systems with MOS or Motorola CPUs it was usually even easier (if more expensive): just pop in a card or cartridge with a Z80 processor. Examples include:
Atari 800 etc.: the ATR8000 module and various other options. (But possibly not totally fair, since the ATR8000 had its own memory as well as a Z80 and just used the Atari as a terminal.)
Fujitsu FM-8, FM-7, FM77: All of these had coprocessor slots and Fujitsu offered Z80 cards and CP/M.
The PET seems to be the one major exception to this. Were there others? (If youāre not sure about the system youāre thinking of, Wikipedia has a List of computers running CP/M.)
Since CP/M required disk drives, I think itās fair to limit answers to systems where the majority of the installed base had a drive, or they were at least very commonly used. (So no ZX81, sorry fans.)
I think itās simpler to find the non-Z-80 machines that had CP/M rather than list off the ones that didnāt. For instance Iām pretty sure that the TRS-80 Color Computer didnāt have an option for CP/M.
Nice! Iām pleasantly surprised to see the Spectrum. Amstradās CPC, too, can run CP/M.
As for those which canāt, the tripwire here is āmajorā - there are so very many micros from that time! I propose we donāt try to pick apart that distinction.
Just a nitpick: the BBC Micro has a āTube second processor interfaceā - not a slot.
The later BBC Master had the same interface, which takes a (very short) umbilical to a box placed to the side of the machine. It also had a pair of headers internally, used for an internal second processor: same logical and electrical interface but different form factor. There was also an option for an empty external box which accepted the internal type of second processor, at extra cost.
I suppose that if we get into the nitty details, technically, youāre correct that there wasnāt an option for CP/M, because there were at least three. :-)
Iām probably in the extreme minority here in that I hadnāt heard of CP/M at the time. I mean, I saw print ads for Heathkit, but I didnāt know anything about S100 or CP/M or anything like that.
So for me, home computers were defined by what I could try out in retail store displays - no mass storage, just whatever you got when you turned it on. That meant the default interactive BASIC interface.
Donāt forget that CP/M isnāt just about the Z80, but originally about the Intel 8080/8085 (to which the Z80 is compatible). Provided thereās a disk drive available, these machines should be capable of running CP/M as well.
Early in the PCās life a popular upgrade was replacing the 8088 with the pin compatible NEC V20 processor. That ran 8088 code slightly faster but also had a Z80 mode that allowed the PC to be used as a CP/M machine (CP/M-86 was one of the OSes available for the PC, but it had far less software for it than the 8 bit version). The most popular CP/M software had already been ported to the PC and DOS at launch or soon after, but some people still felt there were many interesting 8 bit programs missing. That phase probably lasted less than 6 months in 1982/1983.
I can well imagine for business continuity a company might buy a CP/M system to run the software they know in the way they know, rather than hopping to DOS on the PC.
BTW, Amstradās PCW was made up until 1998. I wonder (idly) what other CP/M systems you could still buy as late as that.
And hereās a machine I didnāt expect to have a Z80 add-in for CP/M: