OT-ish... what to do with > 400 relays...

From: ed sharpe <esharpe_at_uswest.net>
Date: Thu Feb 19 23:13:18 2004

an interesting start!
thanks for sharing!
shall look forward to seeing the pics...
this would be a neat 1st hand experienced history to
post up on the museum's web site for the 'kids' to
look at.....


----- Original Message -----
From: "David V. Corbin" <dvcorbin_at_optonline.net>
To: "'General Discussion: On-Topic and Off-Topic Posts'"
Sent: Thursday, February 19, 2004 9:37 PM
Subject: RE: OT-ish... what to do with > 400 relays...

> I will have to look for them, they are deep in storage will other items
> my teenage years.
> A little bit of the history though....
> My father was a wireman/engineering prototype builder. This is back in the
> days when most systems had significant harnesses thay were hand made (with
> lacing cord, no such thing a tie wraps). The harnesses were build
> my placing a full size blueprint on a piece of plywood, placing "nails" at
> all of the junction points and curves, and springs at the end of each leg.
> The wires would them be cut to length, stripped, tinned (coated with
> and placed onto the board. Lacing cord would then be usig to tie the wires
> together (I can still do a half decent running stitch, but can not find
> waxed lacing cord....).
> While my father had quite a reputation in the New York area, and was
> after for may projects by companies such as Grumman, he really did not
> much of a background in how the devices actually worked. On the other
> I was growing up around this stuff (burned my hand on a soldering iron for
> the first time at the age of 2), and was always curious.
> A number of the companies my father did business with had computers (often
> teletype with an acoustic coupler tied into a timeshare service). The
> engineers there would often sign me in, and let me play one of the
> games. This started my interest in computers. These same companiew would
> regularly scrap various prototype and test fixtures. I would take them
> (more often my father actually brought them to me), and scavange the
> One of the most common items (froma company named Beukers Labs if memory
> serves...) were SPDT 6V relays (about one cubic inch in size). I had a few
> hundred of them.
> I had learned about digital logic gates, but had no ready access to any
> integrated circuits. My skills were not good enough to make transistors
> reliably (my fault not theirs). So many of my project wer based on relays.
> figured out how to make inverters, or gates, and gates and latches. I
> started to combine these into larger circuits. At about the same time my
> father brought home a 1967 Digital Logic Handbook. I was completely
> fascinated by M series modules (flip chips) and the fact they could build
> real computer (ok they used transistors, but what the heck). The "project
> was born.
> I started figuring out how to implement a simple instruction set (CLR,
> STORE, TEST, JUMP, READ (Switches), DISPLAY (LAMPS), NOP). The number of
> relays was quickly astronomical (try to build an adder with carry....).
> Since 3 bits was enough to define an instruction, it became the word size.
> Since 3x6 was a standard size for the harness boards (and we had lots of
> them!), I used one of them for the layout. After spending quite some time,
> came up with most of the "schematic" and proceeded to start building a
> harness. Once the harnes was build, I screwed the relays directly to the
> board, and soldered the wires to them.
> Of course it did NOT work...But after much troubleshooting (including
> wripping most of the harness apart, flywiring between various points. I
> the beast to do what it was designed to do (which really turned out to be
> nothing usefull at all... 8 data locations, 1 accumulator, one input port
> bits), one output ports (3 bits), and 16 instruction locations (which as a
> result ment you could only jump to "even" instruction bytes...
> Amazing I was so proud of it. That fall I got the opportunity to be on the
> school districts "new" PDP-8, and the rest of my life was set in
Received on Thu Feb 19 2004 - 23:13:18 GMT

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