Wow! This must have been quite a project!
http://www.cs.pdx.edu/~harry/Relay/index.html

Great photo's Pauluk,
Indead that was a mammoth task to build that computer, good too see that with will a lot of things can be made fully electromechanically. It takes a bit more space, but hobbies are great time spenders, and a challenge to complete something different.
Also the cabinet making has been done very professionally.
Excellent!!

He must have found a couple cases of relays that fell off a truck

Back in the greasy gear machine days IBM did some pretty fancy stuff with solenoids, relays, ratchet counters, brush emitters and such.

I was just thinking this must be how IBM started out, didn't they (or someone else) build big relay computing machines?

By the way, it's still common to see large banks of relays in the field of train coltrol - not exactly the same as a relay computer but I've wondered why they haven't gone over to PLC's long ago.

Radar

IBM built relay machines up until the late 50s and early 60s. Something like a 407 accounting machine read cards in, did fairly complex computations on the data and printed out the result about 120 cycles a minute. It was one transaction at a time, which may involve several cards to complete then print out the result in a report, checks or whatever the desired output would be. This was all done with relays and mechanical ratchet counters.
This required the cards to be sorted and colated in the proper sequence (perhaps the first being the data on who the customer was, the next being the history and the rest being current charges or payments) and that happened on other machines.
It was an interesting bunch of stuff to work on. We also had 357 data entry systems that used relays as scanners, registers and counters.
I wonder if the guy who built this thing is an old retired IBM guy ;-)
I made a tic tac toe computer with relays that was unbeatable. The best you could do was tie.
I used to make lots of relay stuff when I had lots of relays around.
I prefer 4000 CMOS when I make things these days

It's amazing just what can be achieved electromechanically. Just think of the complex register-translators, markers, and other circuitry which was used in pre-electronic telephone exchanges for another example.

You'll notice that he did mske one concession, and that was a 32K x 8-bit static RAM I.C. Trying to implement that with relays would have really made things big!

"Wow! This must have been quite a project!"

It must be a noisy one, too!

radar

I think reliabilty issues and galvanic separation are the issues here.

We use relays in all our substations for the controls eventhough the protection can be electronically, like the SEL or Siemens relays.
The outputs are relay controlled.


Edited for typo's Ray


[This message has been edited by RODALCO (edited 02-21-2006).]

Wow!,
That's cool Paul.
Thanks for the link.

Looks just like my first 286 "laptop" computer I had that practically needed a dolly to wheel around.

Was that an IBM 5162? It was basically the original PC/XT desktop with a 286 processor upgrade and a handle.

Good one Paul,
I've just sent your link of Harry Porter's
relay computer to my Work colleague, telling him to get one of these set up in his office, & scrap his Dell's!!