Relay computers

From: Paul Koning <>
Date: Fri Sep 24 10:03:29 2004

>>>>> "Ade" == Ade Vickers <> writes:

 Ade> At 22:50 23/09/2004, you wrote:
>> On Wed, 2004-09-22 at 11:17 -0700, Vintage Computer Festival
>> wrote: > On Wed, 22 Sep 2004, Jules Richardson wrote:
>> >
>> > > Apologies if someone's mentioned this one before. Quite
>> possibly the > > coolest gadget I've seen in a long time, though:
>> > >
>> > >
>> >
>> > Awesome. It would be great to get stuff like this exhibited at
>> the VCF.
>> >
>> > The web page is pretty smart also. What terrific technical and
>> design > work.
>> Amazing, huh? If I read that right, it's 52 relays though (I don't
>> know any German) which makes it sound rather like a 'simple' relay
>> control system rather than an actual relay computer. I fired off
>> an email to them to see if they'll let me have a nose at the
>> wiring diagrams.

 Ade> I did some back-of-a-fag-packet calculations (i.e. they might be
 Ade> completely & utterly wrong, in which case I'd appreciate
 Ade> corrections) on a relay computer...

 Ade> Assume you want a Z80-type CPU. This has ~8k gates. Typically,
 Ade> it seems to take 1 relay per input to implement any given
 Ade> gate. Now, I don't know how many "x-input" gates there are in a
 Ade> Z80, so I'll assume that - on average - it will require 3
 Ade> relays/gate. Thus, we need ~24,000 relays to implement the Z80.

I think when people talk about "gates" in a logic design, it's
normalized back to the simplest kind: 2 input gates. So that's two

Meanwhile, remember that the original Pong didn't use a
microcomputer. It's just a board full of 7400 series ICs. It's been
too long since I saw one, but it doesn't seem unreasonable to do the
equivalent with 50 relays. For one thing, you don't need a video
generator, just motor controllers for the paddles and ball. And the
sending of ball hitting paddle or wall is done with contacts in the
mechanism, not with the logic itself. So the relay control has to
control motor speed and direction, but it doesn't have to track

Received on Fri Sep 24 2004 - 10:03:29 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:37:31 BST