Relay Computer 2020 Review: Demonstration

[@BiggRanger]

The content and quality of these videos is amazing. They should be used to teach CS in schools.

[@user-yw8sr3uj1w]

Definitely!!!

[@johnwilson3918]

Brilliant! Thanks for showing this. Imagine if you could travel back in time to the 19C and show this off to Charles Babbage. He'd be mighty pissed!

[@edgeeffect]

It's nice how you've done that multi-screen edit, so that we can see everything at once without you having to wobble around with a handheld camera or anything seasick like that. :)

[@paul80nd]

Thanks :) - although if I'd built my computer 'landscape' rather than 'portrait' of course I wouldn't need to do the multi-screen in the first place ;)

[@jbrownson]

Very impressive work, thanks for sharing it. I love being able to hear the sound of a computer doing its work.

[@werdna1969]

This is exactly how I imagined the future would look like!

[@projectartichoke]

A very outstanding computer, obviously a labor of love, and the best looking relay computer ever made in my humble opinion.

[@WeirdscienceTV]

This is a pretty ingenious work, subscribed!!

[@telegraph_hill]

I love the quasi musical beat at 8:00. Well done!

[@Culturedropout]

Amazing! I just had a flashback to Bletchley Park. That's awesome!

[@evmemc]

Thats very cool, I absolutely love everything about your design and setup here, awesome job!

[@brettany_renee_blatchley]

Sounds like a syncopated calculating tap-dancer! 😊 Wonderful device!!

[@OzzMazz]

Sounds like an old fashioned telephone exchange. :) Great work.

[@paul80nd]

I love the sound ... and the flashing lights ... but mainly the sound ;)

[@mirskym]

Bravo! It's clear that you put a lot of work into it!

[@weirdsciencetv4999]

Yes, the one me and the kids made has microcode as part of a rom structure. Address space for it is 5 bits instruction, 3 bits sequence number. Rom size is 256 x 64 bits. The instruction selects which portion of rom to start, the sequence number lets you break down an instruction into steps. The bits control which enable gates are active for connecting parts of the computer together to the busses. The rom is an address decoder matrix with DIP switches at the intersections. We have a biphase clock too, any bits which changes effectively is given time to settle (1/4 clock cycle) on the bus. So it’s kinda like having 16 states instead of 8. Our clock/sequencer is a gear motor driving a cam.

[@paul80nd]

What an awesome way to bring up your kids - love it :)

[@WeirdscienceTV]

@@paul80nd​Aww thank you! Yes the kids laughed and loved the entire course. I recorded it maybe we can edit and put on youtube sometime. But it started out with basic knife switches and light bulb and battery to make logic gate, then we used a relay. Then we made a half adder, then full adder, then ALU, and just kept going. A year later and now they are experts lol! I figured the visceral click clacking of relays would stick with them.

[@CasualSnake_D2]

Oh this is delightful! Well done!

[@ChadLawson3]

This is gorgeous!

[@Homebrew_CPU]

Nicely done!

[@borissinaga]

Blinken liiiiighhtttssss. But seriously, impressive work.

[@hattree]

I love the lights, it's like the WOPR from WarGames.

[@paul80nd]

That's absolutely the look I was going for :)

[@mezzofresh3521]

That's really cool man

[@briandenley]

Amazing work and presentation. Available as a kit someday? Hehe just hoping!

[@paul80nd]

Thanks. Heh, yea, that would be quite a task making this in to a kit ... that said though, there's links to the PCB designs for the newer cards at www.relaycomputer.co.uk/pages/progress/ and I think I'll upload the Gerber files too so you could get any of the PCBs manufactured if you really wanted to make a bit of the computer.

[@prpplague]

awesome work and eemo!

[@TexasRailfan2008]

That amp gauge is about the only part of this that I understand.

[@marcviej.5635]

yes

[@canadianman000]

I don't think you should use a bell when this halts. Instead it should definitely have a mechanical buzzer.

[@HikaruAkitsuki]

So this is what they meant when you said to code the computer in binary, it is actually a hard switch coding.

[@weirdsciencetv4999]

Why do you need so many sequences from the sequencer?

[@paul80nd]

It depends on the complexity of each instruction. Something simple like an addition or moving values between registers can be done in 8 cycles but when you get to things like jumps they're much more complex so take longer (24 cycles in this case). Here's the timing chart for a jump (GOTO): www.relaycomputer.co.uk/posts/2019/11/controller-goto-design/

[@PaulasTechStuff]

Beautiful

[@wizrom3046]

My new computer runs at over 4 Hertz! 😎 "You mean 4 GIGA Hertz... right?" ... "right?? ??" 😯

[@canadianman000]

Why the dip switches for speed instead of a variable control?

[@paul80nd]

At the moment it's running off a temporary clock board which uses a 32.768kHz crystal run through a series of 16 divide-by-2 gates (taking the clock down to 0.5Hz at the last gate). I tap off the result at the last 8 gates (0.5, 1, 2, 4, 8, 16, 32 and 64Hz) and put that through an 8-to-1 selector which takes a 3-bit input to select one of the 8 lines - that's what the DIP switch is controlling. Previously I was using a 555 timer set up that had variable control but I wanted something that had some discrete fixed clock speeds. When I design the proper clock card I might implement both as well as having a more 'authentic' relay ring counter (which will be a fixed clock speed).

[@gabrielafranco730]

What are the small squares and text with lights behind them called? Could use them for a project of mine... Great work 💪

[@paul80nd]

They're these: www.nkkswitches.com/products/illuminated-tactile/jb-series-low-profile-illuminated-tactile-switches

[@gabrielafranco730]

Perfect thank you!

[@maverickstclare3756]

I hear Todd Howard is planning a SkyRim port

[@gorazdnovsak3705]

End looks like Star Trek TOS computer...

[@DJ_Level_3]

What kind of switches are those? I want to get some for a project I'm doing.

[@paul80nd]

Do you mean the main 'paddle' switches? ... if so they're these ones: www.nkkswitches.com.hk/products/Rockers/M/M2018TYW01 with the 'H' caps.

[@paul80nd]

there's a bit more on them in my blog post here www.relaycomputer.co.uk/posts/2014/07/user-interface-data-switches/

[@gauravponnappa8257]

I want one

[@artemonstrick]

what is the highest clock frequency?

[@paul80nd]

The current (temporary) clock is based on a 32.768KHz crystal divided down and at 32Hz the computer works fine but at 64Hz the relays start locking up. The maximum will be somewhere between those two values (if I had a variable clock) but 32Hz is quick enough.

[@TheCubeFactor]

where do you get the switches?

[@paul80nd]

Most of them are from www.nkkswitches.com

[@TheCubeFactor]

@paul80nd thanks!

[@jaimdiojtar]

i wanna see it doing 20 decimals of pi

[@paul80nd]

Yea, I'm up for that - challenge accepted :)

[@IsawU]

This is so beautifully useless. Nice work

[@kraio-sfu]

Oh I’m sure he knew going into this that it would be supremely slow. But clickety clackety/flishity flashity!