Zilog Zeus

Jeff Jonas jeffj at panix.com
Thu May 8 09:40:12 CDT 2008

From: Matthias Knoth <mknoth at earthlink.net>
> does anybody have information/source code/anything
> about the Zilog Zeus System? It is a System III Unix derivate
> running on a Z8001 16bit CPU

Gaaah, it's coming back to haunt me!
The NJ Computer Museum has a Zilog System 8000 model 21
what's probably running that!
One of my AT&T IS consulting assignments was running URTS
(Unix Regression Test Suite) on the SVR3 port
and examining the source code.
I'm unsure I have any of that on tape or printouts :-(
The comments were amusing such as the Z8000 CPU
forcing the Z80's "RETI" instruction
on the peripheral bus to reset the Z80 peripherals chips
interrupt daisy chain.  The comments were something like
 	ld  foo ; now watch my lips ...
 	mov bar ; RE-
 	ld  baz ;
 	mov qux ; -TI

That's the first place I saw "deadbeef" as a magic number.

I really liked the System 8000 as a development system
since it had a firmware monitor that could be invoked
in case of a system crash to poke at the RAM.
I think that's where I learned how to repair the system
using the stand-alone bootable tapes such as
SASH: Stand Alone Shell,
and SADIE: the diagnostic tape.

When Exxon owned Zilog (around 1982), they had an office in
Rockefeller Center (NYC) for their office automation
featuring the Zilog System 8000 running Zeus.
Back then, breadbox sized Z8000 systems running Unix System III
were common, such as the Onyx, so the Unix manuals were all around
(Then 68k based systems took over, then Intel x86).
I like in an apartment, so I can't save 'em all :-(

From: Dave McGuire <mcguire at neurotica.com>
> I ran a Zilog System 8000 running Zeus daily
> for quite a while back in the late 1980s.

But did you get to peek into the kernel
or use the maintenance programs?

From: "Mark Davidson" <mdavidson1963 at gmail.com>
> I'd love to hear what people have as well...
> I remember "porting" an RM/COBOL system for a doctor's office
> from a CP/M system to ZEUS and loving the system.
> I've never seen any on the collector/used market

I remember seeing 2 on the back of an old pickup truck,
for sale, at the Trenton Computer Fest in the late 80s.
Talk about a fall from grace!

The only RM/COBOL I remember seeing was a manual for the NCR Tower,
but I was a firm Unix/C kinda guy by then.

-- Jeff Jonas

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