Relay Computer - Prototyping Board & Instruction Register

[@AJB2K3]

There is something musical and pleasant to listening to those relays.

[@rubenhillier770]

This is starting to take shape, the prototype board is a very good idea.

[@veryberrykeri]

always excited to see more progress!!

[@dipdoting]

Thank you!

[@txd]

The production value keeps increasing :D

[@dipdoting]

Thank you for noticing - trying to up my game with each video 😎😬

[@txd]

Aww yeah. Time to open a beer and watch this :D

[@skeezixcodejedi]

This is really a thing of beauty :) Its really fun and addicting building up an SBC or home designed computer, but doing with relays just is so fun. And insane. But mostly fun :)

[@dipdoting]

The process has taught me a lot in both design and low-level CPU functions - it is a bit insane and I'm always surprised when I plug in a new board and it actually works 😁

[@GegoXaren]

This was interesting, as always. Keep up the good work!

[@dipdoting]

Glad you enjoyed it!

[@awesomecronk7183]

You've inspired me to FINALLY build the relay computer I've wanted to build for years! ALSO nice intro!

[@dipdoting]

Thank you! The intro was also a lot of fun, love doing stop-motion stuff! Glad to hear you're going to build one, let me know how it's going!

[@awesomecronk7183]

@@dipdoting Well it's a much more complex design that probably would be best left to TTL. The ALU alone is about 87 relays so far. It's my 5th or 6th scratch computer design and I put a lot more effort into making it capable than I did into making it small. We'll see how much I regret that later on!

[@derekchristenson5711]

What a cool project!

[@dipdoting]

Thank you!

[@bradinatorhd4500]

Love the new prototype board design!

[@dipdoting]

Thank you!

[@420Ayan]

Thanks for sharing, I have been waiting to start my own project. Going to university now so I can finally start something like this and this is really good motivation and insight :)

[@dipdoting]

For what it's worth, I started with a cheap set of breadboards, a few relays, LEDs , resistors, jumper wires and a battery. Oh and I guess diodes, too...I always forget about those 😬 The only thing I'd recommend is to buy good quality breadboards - they are a bit more expensive but they are well worth it!

[@420Ayan]

@@dipdoting I have had to experience first hand the horrors of cheap breadboards, having to troubleshoot a circuit only to realize halfway through that one needs to troubleshoot the breadboard too. If there is one thing I'd happily pay a premium on it would be breadboards haha Cheers.

[@setlonnert]

Very interesting to follow. Long time ago I intended to write a paper (in history of technology) about the first Swedish computer BARK (you can find an article of it on Wikipedia in Swedish, but make an automatic translation to English as the English version doesn't really have content at all). It was all relays and some of the documentation could be found at the national archive. Some were still under seal (much military hush, hush). Always wondered how it worked, and now I can at least imagine how!

[@dipdoting]

Wow! Thank you for that -- In all my research I have never read about this BARK before! 32-bits, 50 registers and 8,000 relays!!!! What a monster! I hope that's in a museum somewhere!

[@pdrg]

Great work. Just a query - at 14:23 on the backplane it looks as if the reservoir capacitor is doming out a little, could it be failing? May be worth checking/bearing in mind if you get errant behaviours.

[@dipdoting]

Good eye! I'm thinking I'll need a larger capacitor...there'll be one on each backplane to split the load.

[@charlieb.4273]

Like the line in Jaws. You’re going to need a bigger backplane. I thought of this before you showed the ribbon daisy chain setup. Well done. Following with great interest. Charlie in Virginia.

[@dipdoting]

Haha I was so close to using the line a couple of times but was worries no one would get the reference! I'm going to squeeze that into a future video...thank you for following along!

[@strange67x]

Sure great idea ! 🙂 But you should add some capacitors to buffer the voltage drop over your various 5 volt lines for these bunch of relais !

[@mheermance]

I like your prototype board. With TTL CPUs people store the microcode in an EEPROM, but you can't do that. So it will be interesting to see how you build it out of relays. I suppose a diode ROM is possible.

[@dipdoting]

Yes, it makes for an interesting time decoding the instructions, for example the micro-code to transfer a value between registers will take ~10 relays.

[@sashimanu]

The sound it makes reminds me of teletypes. If your machine can run at 10 cycles per second it can load programs from a 8-bit punched tape reader, such as one included in model 33 ASR teleprinter, or a from a separate unit (much smaller than a teletype)

[@dipdoting]

I LOVE the sound of teletypes; having one is on my bucket list. Always been fascinated with how they are mechanically synchronized and actually passed serial data so many decades ago!

[@CameronJamesH]

What's the smallest instruction set you can get away with?

[@mheermance]

Google the PDP-8 and take a look at its instruction set. It had eight instructions, one of which allowed embedded microcode. Theoretically it is possible to build a single instruction set computer using conditional subtract (SUBLEQ), but no sane person would want to program it.

[@awesomecronk7183]

I have also done a single instruction computer, but my instruction was copy. Everything was mapped to an address and shared the same bus.

[@mheermance]

@@awesomecronk7183 that sent me down a rabbit hole of triggered transport architectures. I have never heard of that before.

[@dipdoting]

I guess it depends on what we want it to do. If the only instruction was a "NOP" then it would just happily click away with the clock. Like what @mheermance said, probably around 8 minimum to be able to do some interesting stuff.

[@AppliedCryogenics]

Will the data bus gating to PC become useful when implementing a JMP instruction?

[@dipdoting]

The architecture of this machine doesn't load the PC from the data bus directly as the data bus is only 8 bits. But, we can load X and Y with two 8-bit values that become the 16-bit XY value that can be transferred to the PC via the Address Bus.

[@ReneKnuvers74rk]

Is there a particular reason why you didn’t hardwire the gnds for the relays?

[@awesomecronk7183]

You don't always want a relay coil wire directly to ground on one side. One example is doing XOR on the coil where you have one source/sink input to each side of the coil. If one of them is pulling to VDD and the other to GND, the coil energizes.

[@dipdoting]

Actually, they are all grounded --- I just kept the pins there for symmetry. Originally I was thinking of not using a ground plane because sometimes you may want to activate the relay using the GND (like from a Darlington - that's what I did on the Static RAM memory card).

[@mutzbunny]

what Wirewrap tool do you have, ive been searching for one, but couldnt find the one i need. yours look like exactly what i need

[@dipdoting]

It's a Jameco Benchpro WWT-100, and inside the handle there's a wire stripper as well.

[@jyvben1520]

enclosure, active cooling ? internal or external power ? com port ?

[@dipdoting]

Lots to think about for all of these - likely just a good old fan for cooling, internal power supply, COM port running a 1 baud 🙃

[@faneuil1]

take my damn money! I want one! (seriously)

[@faneuil1]

and love the logo - got merch??

[@dipdoting]

Merch has crossed my mind 😉 I'll try to come up with something relay interesting. As for the boards themselves, I'm going to post some designs soon once I find a good site.

[@rubenprovencio-b1u]

donde puedo encontrar esquematicos

[@dipdoting]

Publicaré los esquemas una vez que la computadora de relé esté terminada. (Lo siento si esta traducción no es buena, usé el traductor de Google.)

[@rubenprovencio-b1u]

@@dipdoting si está bien la traducción

[@txd]

Hello Mr DipDot. Is there coming a new video soon? I need my dose of click clacks :D