DAVIAC homebrew relay computer

Here’s a still from Dr David Warren’s short video showing scale and blinkenlights:

Schematics and architecture details for DAVIAC now available at http://daviac.net

Here’s an earlier video, also short:

Previous relay-computer related topics:
A modern 8-bit relay computer from scratch
More relay computers, on video
Relay Power Pi Machine


That’s fascinating.

00:33 in the video, top row of pannels, second panel from left to right, I noticed an 8 bit incrementor there evidentiated by the lights pattern. On top of it there are other 4 bits, so I guess the whole thing is an instruction pointer (?) on a 4k RAM that currently runs at around address 1024?

Can’t tell anything else from that machine, but the pattern stood out to me. It could also indicate that all instructions have precisely 1 byte since I didn’t notice skips in the increment process.

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Good sleuthing… but note that the schematics are all there on the website - so reverse-engineer it only if you feel very motivated!

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Indeed it was a 12 bit instruction pointer, looking at the info you provided. And instructions also seem to be 1 byte whole.
Now I’m thinking, why did they put the upper bits of the addressing on a different row? Were they considering those as 256 byte pages counted by the index above?

I am not really aiming to reverse engineer a machine in this case, I am more fascinated by the thinking of the engineers behind that. Those pannels are an interesting reflection into that.

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