Subject: 77/68 computer (was Seeking good home...)

From: "Hills, Paul" <[email-masked]>
Date: Sun May 4 01:33:00 2003

Andy,

I guess the Electronics and Computing Monthly magazine and Stirling
Microsystems must have based the design on the ACC one. The ECM design was
on 8" square boards too, single sided tracks (you had to run loads of wire
straps!). I still have all the documentation for it, paper-based at the
moment.

There was a choice between a 40x24 monochrome display board implemented
entirely in 4000-series CMOS (which I built), or a newer colour board with
64K RAM and a Thomson EF9365 Graphic Display Processor. I didn't build that
since the cost of 64k RAM in 1982 was prohibitive! That processor could draw
at 1 million pixels per second - impressive for 1982.

Some of the documentation is published by Newbear (Newbury Electronics), and
some by Stirling. One day I'll get around to scanning all the docs in for
general availibility.

paul

-----Original Message-----
From: Andy Holt [mailto:[email-masked]]
Sent: 19 April 2003 20:40
To: [email-masked]
Subject: RE: Seeking good home(s) for old hardware [UK]

> Getting on 20 years ago I built a 6809 based computer from a
> series running in the UK magazine "Electronics & Computing
> Monthly", called the 77/68 system. This was based on the SWTP
> stuff but was marketed through a company called Stirling
> Microsystems in Baker Street, London. Does anyone else here
> remember that system? ...

As I remember it, the 77/68 was published in the ACC newsletter (not in
E&CM) - the original was a rather neat design by Mike Lord on 8" square
PCBs.

I built a seriously extended one of these (which eventually "fissioned" into
two complete systems - connected by a homebrew network that was a sort of
very cheap slow ethernet). Some boards were from the original design -
others I designed and implemented myself ... most notably including a 6809
board (the original was a 6800) with the only technical data being a pin-out
and some other vague descriptions in a Byte article. It was a couple of
years of successful use before I discovered that I was feeding the clock in
through the "wrong" pin!
Amongst the peripherals that this system acquired was a large Calcomp
plotter surplus from the University mainframe.

Unfortunately most of the hardware and documents have now been recycled or
worse.

Andy