Emulators of Classic Computers

From: William Donzelli <aw288_at_osfn.org>
Date: Wed Jan 21 00:04:57 2004

> ...this sounds as though it's the converse; this sounds as though tube
> transit times are inconveniently _high_.
>
> So I don't get it.

In theory, computing tubes would not use much power at all, so one could
space the cathode-grid-plate structure very close, and get the super
speeds due to the very short distances involved. Imagine tubes as small
today's transistors - the speeds would be fantastic, as the electrons
would speed right thru the micron of vacuum much faster that a micron of
silicon.

However, the real world hits the tubes far before element spacing gets
this tiny. The breakdown voltage between the cathode and plate probably
hits first - too close, and the electrons will simply jump over on their
own, like a spark. Likewise, with very short distances, capacitance will
become a big issue. The best conventional tubes top out somewhere around 4
GHz, and these were only good for small amounts of power. They were a
bastard to build, as well.

So, in a perfect world, with no capacitance or power problems, tubes
would be great.

William Donzelli
aw288_at_osfn.org
Received on Wed Jan 21 2004 - 00:04:57 GMT