General public machines (Was: Altair 8800 name Was: Re: Altair 680 Expansion Boards?

allison ajp166 at
Fri Dec 23 09:30:00 CST 2016

On 12/23/2016 07:18 AM, Tor Arntsen wrote:
> On 23 December 2016 at 05:45, drlegendre . <drlegendre at> wrote:
> urs was no exception, and I thank you for it.
>> For one, I hadn't known that CP/M was written originally to the 8080.. I'd
>> always assumed it originated on the Z80.
> There are only 8080 instructions in CP/M, not a single Z80-specific
> instruction. CP/M came about around 1974, the Z80 in 1976.
> All the CP/M computers I used had a Z80, but that's just shows what
> was popular at the time.
Yes, that was correct CP/M (DRI) was 8080 code that executed well on z80.
However the BIOS could be entirely z80. And it was not uncommon
to replace the CCP with CCPZ or ZCPR also using Z80 additional opcodes.

Actually the original CP/M V1.3 and 1.4 were written in PLM for 8080.
The V2 and 2.2 versions might have been in assembler but still 8080.
8080 compatability was important as there were 8080, 8085, NSC800,
Z80, Z180, and Z280(late) all could run CP/M.   And that also lead to a
up scaling for 8088/86 and off shoots (early PCdos).

The follow up P2DOS, Novados, ZRDOS, and Z-system, were  indeed Z80 only.
Those were coded by other to be compatible but improved.

It was common to have a Darth Vaders lunchbox (Kaypro) running one of the
CP/M hybrids or clones rather than pure CP/M.  The modularity of CP/M
for that.

Classic examples of that here are:

*NS Microdisk system (5.25" SD floppy) in the 8080 Altair 8800 running
CP/M 1.4 (lifeboat).
*Netronics Exploror running CP/M 2 with MDS disk (765 floppy DSDD
3.5inch) with
  enhanced CCP and the core cpu being 8085.
*NS* Horizon chassis (z80) running CP/M2 with MDS DD (stock NS version)
*NS* Horizon chassis (z80) with mods running CP/M2 with my own BIOS and
 Teltek disk 32mb. also  8/5.25/3.5 floppies and smart DMA controllers
for each.
*CCS Z80 powered CP/M system with floppies (8/5.25, or 3.5)
*SB180 running Z-System on Z180 with miniscribe 20mb disk and QD (DSDD)
*Compupro (Z80) running CP/M2 with full Compupro disks (disk 1A, disk
3(32mb), M-drive)
and a MPX-1 (8085) slave for IO.
* AmproLB+ running ZRdos (Improved CPM 2) z80 with SCSI disk 45MB and
DSDD 3.5" floppies.
*Kaypro 4/84 running CP/M2 (With Handyman, Ramdisk, Advent turbodisk and
Disk personality
 card running CP/M2 and ZCPR.
*Z280 S100 homebrew card in spare cage (maybe IDS) with 4MB ram,
Compupro MPX1 slave
and assorted Compupro DMA disks (1A and 3).  Runs CP/M core with my own
and CCPZ and BIOS (in IAnd D space with user/system spaces).

This is a sample of system I have some going back to day one that all
ron some flavor of CP/M
on the wide range of CPUs around in that era.   They all can run all of
the base aps but some
products were Z80 (or 180 or 280 or NSC800) only.  However many of the
aps like MS Basic,
Multiplan, DBASE, Vedit, and BDS-C could run on 8080 but knew how to use
the z80.  This is part
of why it was not unusual to see some CPM systems still in commercial
use in the early 90s.


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