Talk Of Building A Computer...

From: Philip.Belben_at_powertech.co.uk <(Philip.Belben_at_powertech.co.uk)>
Date: Thu Nov 20 04:19:18 1997

Kevin McQuiggin wrote:

> Hi Tim:
>
> If you're going to try this, I'd suggest starting with something simple
> like an adder or a flip flop, or a register. You'd get an idea of what
> would be involved with a simple processor. But I think it would end up
> being pretty expensive.

[...]

Tim Hotze had written:

>Hello... some time ago, there was talk of building a computer, and now I
>think that I've got a (bad, possibly) idea. In the earlier half of this
>century, transistors weren't avaible... vaccum tubes... huge ones, but
>now, the transistor has made small ones possible. My point: If we were
>to take a tubed design, and re-build it with transistors, we could
>probably make it a decent size.
> So, what da ya think?

I think there is something even more fundamental here. Valves
(thermionic, in tubes) have quite different behaviour to trannies.

A JFET behaves fairly like a triode, but designs that use pentodes and
nonodes and things as multi-input gates are going to be very difficult
to translate.

Of course by the 1960s there were somve very nice valves around that
weren't available to the 1940s computer pioneers - the 7586 nuvistor
springs to mind: a very nice triode in a metal can about 1 inch tall
including pins, and less than half an inch in diameter. Can't remember
the spec, though. Such devices could make a valve machine quite a bit
smaller than Colossus, Eniac, Edsac, etc.

Or if you want to be way out, what about tubes with several valves in?
Things like double diode triodes are quite common, and someone even put
most of a radio set into one tube (passive components and all).

So how about making our own. A tube containing, say, a 4-bit D-type
latch? Make a few in that range and a valve computer becomes almost
manageable! Besides, the smaller it is, the faster you can make it...

Philip.
Received on Thu Nov 20 1997 - 04:19:18 GMT