Vacuum tube logic thing

From: Peter C. Wallace <pcw_at_mesanet.com>
Date: Mon Feb 2 23:39:41 2004

On Mon, 2 Feb 2004, William Donzelli wrote:

> I'll give this list a shot a something meat I have had for a while -
> maybe I can get a nice trade.
>
> I have a big logic trainer that I would like to move on. It is pretty
> neat and unique for three reasons:
>
> 1) It is based on vacuum tubes. Inside are a number of 12AX7oids that do
> the work. I think this dates to the very late 1950s.
>
> 2) The logic is really odd. It is binary, but the logic levels are not
> voltage levels, but phases. Hell of a way to run a railroad, in my book.
>
> 3) Its Japanese. Yes, Japanese. Apparently part of an early minicomputer
> project that came out of Japan called Parametron.
>
> So what I have is a really odd duck - a Parametron LT-2E, with power
> supply, spares kit (with spare tubes!), and the reamins of a manual. It
> is a pretty big desktop unit, but I think I can ship it FedEx ground in a
> couple of boxes (from 10512).
>
> As of now it is untested, but tomorrow I think I might look into powering
> it up. There is some paint flakage and a little corrosion in the aluminum
> body, but nothing to scream about.
>
> So I am fishing for a trade. A good trade, as I know this thing is worth
> some real money. What do I like? Big is good, old is good, IBM or Univac is
> good, but I am open to ideas. I can trade up or down with cash, if we can
> not quite equal things out.
>
> Try me.
>
> I'll try to get some pictures shot tomorrow.
>
> William Donzelli
> aw288_at_osfn.org
>

"Digital Computer Design Fundamentals" - Chu - 1962


Has a full section (about 4 pages) on Parametron logic, here are a couple
little excerpts:

"The Parametron, developed by Goto of Japan, is a parametric phase-locked
subharmonic oscillator (PLO). As described in chapter 6, a PLO is a
resonant circuit with a reactive element varying periodically at a pump
frequency fp; the resonant circuit produces a parametric oscillation with a
frequency fo which is the second subharmonic of the pump frequency (or fp =
2fo). The parametric subharmonic oscillation has a remarkable property in that
the oscillation has two stable phases which differ by 180 degrees as shown in
figure 6-35. These two stable modes of oscillation represent the binary
states; hence a PLO is a binary storage element..."

"The parametric oscillation is not a new phenomenom. Its application to the
digital computer was independently conceived by both the late Von Neumann ant
Goto of Japan at nearly the same time (1954) . The Parametron has been used in
several digital computers in Japan.
"


Peter Wallace
Received on Mon Feb 02 2004 - 23:39:41 GMT