[vcf-midatlantic] Xerox 16/8 M92 computer

Herb Johnson hjohnson at retrotechnology.info
Sun Aug 4 18:16:06 EDT 2019

> On Sat, Aug 03, 2019 at 11:13:28PM -0400, Evan Koblentz via vcf-midatlantic wrote:
>> >> Does the museum have or need this?
>> We have a couple of 820s, but we don't have this. Do we need it? I don't
>> know... anyone have thoughts about that?
> If you have other good examples of the dual processor PC with CP/M showing the
> attempt to bridge the generations another may not be that significant. The 
> page says it may had a little better implementation than some with the 
> concurrent processing.

There were a number of microcomputers in the early 1980's, which 
incorporated both an 8085 and an 8088, or a Z80 and an 8088. The 
Heath/Zenith Z-100 (Z-121) switched between an 8085 or an 8088. The 
Compupro 8/16 used an 8085/8088 S-100 CPU card, similar circuits. I 
believe NorthStar had an 8088 board option for their Z80 based Advantage 
(non-S-100 computer). There are other examples. Likewise, some MS-DOS 
computers ran an ISA bus Z80 card (Baby Blue, etc.).

Why do this? Because of the rise of MS-DOS during the age of CP/M-80. 
Keep in mind that through the late 1970s and into the 1980's, CP/M-80 
was the leading Intel-compatible operating system. These 8088 options 
were ways to provide some kind of compatibility and future-support, for 
MS-DOS products and for "Big Blue" IBM. The Z80 cards for IBM PC's, was 
a way to run legacy software - until PCs were fast enough to emulate 

It's a period of time that's becoming harder to appreciate; it's not in 
the experience of persons now under 40 or so.  It doesn't fall nicely 
into one "IBM-PC, CP/M, Mac, videogame" category. Life is messy that way.

Herb Johnson

Herbert R. Johnson, New Jersey in the USA
http://www.retrotechnology.com OR .net
preserve, recover, restore 1970's computing
email: hjohnson AT retrotechnology DOT com
or try later herbjohnson AT retrotechnology DOT info

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