31 Oct
2013
31 Oct
'13
11:45 a.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of Josh Dersch
Sent: Wednesday, October 30, 2013 8:49 PM
To: On-Topic and Off-Topic Posts
Subject: Re: Random UNIVAC item...
On 10/29/2013 1:07 PM, Brent Hilpert wrote:
For those who aren't familiar with dekatrons: the folks at TNMOC were explaining to me
how they work in computer circuits. The dekatron's state transitions with an input
pulse, taking one of ten states. One cannot directly (electronically) read a
dekatron's current state (although it's obvious by eye!). So in order to read the
state, one cycles the tube until it emits its 'index' pulse, meaning it is now
back to its base state. Subtract the number of pulses needed to get it to that state from
ten and you know where it was! Of course, if you want to retain that state, you must now
cycle it with that number of pulses, to return it to where you found it. A similar idea
to the read-restore cycle of a core memory unit, just with more states.... -- Ian
On 2013 Oct 28, at 7:01 PM, Josh Dersch wrote:
Sure, that'd be very interesting to look at. When I get some time I want to
figure out how this thing works...
Thanks,
Josh
Grabbed this as it triggered both my
"interesting numerical display
device" and "old computer" reflexes:
http://yahozna.dyndns.org/scratch/misc/univac.jpg
It's labeled on the back (roughly, as things don't line up
particularly well):
Magtrol, Inc.
DYNAMOMETER HDE-500
MODEL HD-705
SERIAL NO 511B341
TACHOMETER 811E342
MODEL
SERIAL NO
And riveted to the back is a placard reading "SER 2U02-2"
Inside it's completely tube-based, no solid state electronics at all.
Not counting the Dekatrons, there are 9 tubes in this thing, one
branded "UNIVAC" on the base, the rest appear to be RCA. It looks
like it contains an electronic tachometer of some sort. I can't seem
to find a date code on anything. Any ideas on what this might have
been used for, and how it would relate to UNIVAC?
I can provide more pictures later if anyone's interested, once I get
a chance to disassemble it a bit...
Very cute. Between 'dynamometer', 'torque adjust', and 'Magtrol'
I was
going to guess something to do with calibrating the mechanics of the
tape drives.
The dekatrons are likely the display for the tachometer function.
Photomultiplier tubes were sometimes used as the tachometer sensor for
such counters.
I can provide schematics of a couple of dekatron counters to give an
idea of how dekatrons were used in-circuit, if of interest.
