Emulators of Classic Computers

From: Tom Jennings <tomj_at_wps.com>
Date: Fri Jan 23 18:11:01 2004

On Thu, 2004-01-22 at 19:01, William Donzelli wrote:

> > THe electronic design was abandoned for now. Basically I was to
> > (will...?) build a 4 x 4 switched cap memory which will be a nice
> > reality check on flops, tubes, etc.
>
> Please keep us informed.

Will do!

> Subminis might also be a good choice, if you can find them. They "never"
> go bad. I don't think I have ever found a bad one. Their reliabilty was
> due to production in a clean room environment using very high purity
> materials. One interesting side effect was that submini tubes lost their
> sockets - the things were soldered right into the circuits, as the sockets
> became the most failure prone components.

They are a good choice. The US gubbamint just (well a year or two ago)
dumped huge amounts of them, allegedly spares kept for existing equipme
nt went over 20 yrs old. There were some ship-board computers built with
them, soldered right into the PC board. Hell they're rugged, as they
were first developed for proximity fuzes in torpedos and shells!

> Most computer tubes were also built in the same clean room environment,
> and also tended to be very reliable. In the good old tube computer days,
> there would be a flurry of tube swapping for the first few months, maybe
> a year, of the computer's life, but then as the weakling runt tubes were
> purged, the machines became quite reliable.

I can totally see that scenario.

> The biggest advancement was the use of the IERC tube shields - the type
> that have ribbing inside to conduct the heat away. It took ten years, but
> the industry finally figured out the old style tube shields were a really
> dumb idea.

Yeah, glass is a poor conductor of heat! I suppose lots of forced air
works too, but is always trouble.


> The military radar things, specifically for IFF systems, had good power
> supplies. They were digital system, after all (specifially SIF encoders
> and decoders).

See?! :-)
Received on Fri Jan 23 2004 - 18:11:01 GMT