Relay Computer ep. 5 - Building the ALU multiplexer

[@frac]

Great videos. The concept is really starting to click.

[@gorillaau]

Machine Geek It has a certain clack to it.

[@jameswest7945]

Great videos, come in handy for even simple industrial control cabinets in the modern age still

[@hellfiremissle4907]

In your last video i just realized that you missed out on a very easy to implement operation that does not make your computer faster on a technical level but reduces the operation you need to do for some applications: the shift operator. As you can reduce the amount to of add operations when programming it by multiplying to the closest 2 power of two via shift and then adding (or subtraction if you use 2-complement and what ever suits you better), i can imagine that it would have some possible application working with 16 bit numbers. Also i have to throw it in here... i love this project of yours... it is awesome

[@monad_tcp]

square wave music fits so nicely. time for building a square wave synth out of relays !

[@LeonirZimmermann]

Brilliant work. But where is he?

[@6infinity8]

This series is so satisfying. Keep up the good work!

[@vincentolesen8323]

Looked forward to the continuation of this series! Good job - greating from Denmark!

[@abQUINTON1]

Just found this series, excellent work! Keep it up.

[@edgeeffect]

This is a great series... it's a pity you don't make more episodes more often... but it's worth the wait because your production and content are very very well done..

[@LeonirZimmermann]

Yes, is a great and brilliant work! But where is he?

[@kenpeter3767]

Once you have 4way multiplex, only need feed a truth table for logic you wish to perform. Spare poles form another 4way to ground carry on 00, propagate carry as-is on 01 or 10, or generate a new carry on 11. XOR logic output vs carry input (not carry out to next slice) for a final result. Difference across a final relay coil can give us that XOR. Spare pole of final may also pass a zero flag (which begins high) or ground it. Be sure to put a diode or MOV across each coil to suppress sparks. Differential XOR demands a bridge or MOV solution. Generate should not switch directly to the high rail, but to a control that may disable carry for pure logic. Set your truth table to XOR when adding. All this in four DPDT.

[@ralphlouis2705]

Best lesson ever

[@weirdsciencetv4999]

Just make a microcode lookup rom, whose registers has as many bits as there are select lines. Then your rom could have following structure: 5 bits, “opcode”, 3 bits is sequence number. So each opcode (up to 32 of them) can have 8 steps, each step activates select lines for each step of the operation at hand. So your rom table has 256 entries possibly, whose register width is as wide as the number of total select lines in your machine. The rom can be an array of dip switches. This way only decoder needed is a 5 bit address decoder and a 3 bit address decoder, the grid array addresses your ROM table. Your opcode read from RAM into the instruction register addresses the first 5 bits of rom table, the next three bits are from your clock sequencer.

[@puneetnayak4620]

All vedios are great!!

[@TinNguyen-HEICA]

thanks for making great videos

[@angelagray8049]

Thanks for another great one!

[@Zenas521]

Cool video. High quality as usual. To everyone else, make sure to at least give a thumbs up if you enjoyed. Thees are real fascinating videos.

[@RM-wi2su]

loving the new content, keep it up!

[@michaelanderson654]

Are you selling any kits? This looks like fun

[@josedominguez2021]

Nice vdo again. i want to see all them... thanks a lot. Every time i see better.... I love relay,s. i can do a flip flop tipe D with relays.....do you???

[@royvandam]

Hi cool project and nice nicely executed! Btw I noticed @4:12 that the left pin of the second diode from the right hasn't been soldered properly. Maybe you already fixed it but, it looks like it just connects :)

[@royvandam]

Ah never-mind I was too quick, in a later shot it has been fixed.

[@ProtoG42]

Keep up the great work! Where did you buy the relays?

[@theredstormer8078]

Does this work with 5 pin relays if I connect the coils of 2 together? 5 pins are all I have.

[@albertsandberg]

Yeah, that'd work but double the relay count.

[@Nebulous-39]

How do you get all those custom PCBs? They seem very expensive in low quantities like that. Do you have a way of making them yourself?

[@ClicketyClack]

There are a lot of companies out there that will make small-batch prototype boards for you. As long as you're willing to wait a few weeks and use pretty basic specs (two layers, low tolerances) it's not too expensive.

[@Tuetuopay]

Sooooo many choices for cheap PCBs ... DirtyPCBs, OSH Park, JLCPCB, Seeedstudio, ...

[@diemorijsdijk1831]

Hey clickety clack, What do you want to make with all of those relays What functions should it have? Just curious

[@ClicketyClack]

It's going to be a fully programmable (but very simple) computer.

[@diemorijsdijk1831]

Clickety Clack do you have any idea of how many relays you would need?

[@ClicketyClack]

Between the ALU and the three main registers I believe I'll need a total of 328 relays; for the sequencer, I/O and other miscellaneous parts I'm not sure yet since I haven't finished designing them.

[@diemorijsdijk1831]

Clickety Clack not bad, i guess, gotta count mine as well, but im going to use transistors becouse they are super cheap, if prices were equal i would have used relays :)

[@nonohate]

Hey, could you make the Gerber files available for free download or paid download at some point, it seems like a project I would enjoy

[@kenpeter3767]

Why redundant arithmetic and logic before the multiplexer when MUX are perfectly capable? drive.google.com/file/d/133fmynxjcyRbONJITlNFItSr7aQqz8L8/view?usp=share_link drive.google.com/file/d/1eemAOT77ut0-isMaVaVbfw-9TxhC0q73/view?usp=share_link 1st example wired for carry and saving two control lines, might offer a slightly easier build. 2nd example wired for magnitude comparison, and no saving tricks, much easier to understand. Ken KD5ZXG

[@kenpeter3767]

Also, relay coils of the magnitude (or carry) chain do not depend on carry to ripple, only series prefixes A vs B.