How were 32-bit minis built in the 70s/80?

steven at steven at
Sat May 11 19:50:18 CDT 2019

Warren said
> I'm building my own 8-bit CPU from TTL chips, and this caused me to think:
> how were 32-bit minis built in the late 70s and early 80s? In particular,
> how was the ALU built? I know about the 74181 4-bit ALU, and I know (from
> reading A Soul of a New Machine) that PALs were also used.
> Did companies get custom chips fabricated, or was it all off-the-shelf chips
> with a few PALs sprinkled in?
> Thanks, Warren

I could be remembering incorrectly but I think the Gould PN6080 mini we had exclusively for third year
comp sci at Macquarie Uni in the mid/late 80s was 32-bit made up of AMD2900 family logic (2901 ALU's).

I can't verify that now as it's hard to find anything much at all about the Gould mini's on the web (they
advertised them as superminis back then) but our machine running UTX/32 was pretty easy to bring to a
complete crawl with students all trying to get their Prolog assignments running before deadlines.

The lecturer didn't like us using 'cut' so the stack used to grow enormous and things would go downhill
from there. That, and the two disks - one good one that had the system and staff accounts filesystem and
the other chronically dodgy one that held the student accounts and temp - is about all I remember of it.


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