Logic Unit PCB - Making an 8 Bit pipelined CPU - Part 90

Logic Unit PCB - Making an 8 Bit pipelined CPU - Part 90

0:00 Introduction
0:33 EDA
13:25 Solder
17:48 Install and Test

[IslandHermit]

Watching surface tension pull those SMCs into position never gets old.

[Minoz]

It must have felt great to take away all those breadboards in a single go, you got the design right at the first try too!

[rayk]

Watching you make the PCB designs is absurdly satisfying, thank you very much for sharing this!

[rlbjr]

Yay! Great stuff James! Not to jinx you, but I'm really glad that the last two boards have worked first time... that has to be a really satisfying feeling!

[KingJellyfishII]

I find it oddly satisfying shrinking everything down into PCBs. Great work, especially with almost everything so far working first try!

[lawrencemanning]

Awesome stuff! The diode matrix is going to be a very interesting section of the overall design.

[alessiocaffi]

well done James, your CPU is too nice, it deserves a 128x64 dot LCD.
(BTW, saw your RISC-V comment, yes nice stuff )
Cheers.

[brandonmack]

I was literally thinking how I was glad I didn't have to wait to see the finished board, when you said the very same thing 😆

It's great to see how much more space-efficient PCBs are than breadboards (though the reason is pretty obvious)

[AjinkyaMahajan]

Great work. And completed with perfection.
Cheers ✨✌

[jerril]

Thanks James. It's starting to look like a thing. Hopefully the next two boards turn out as well. Take care.

[rickdearman]

Another great video! Unfortunately for me, it highlighted a mistake I'd made in my own ALU design and I need to yank some wires out and start the logic part again. Oh well, 3rd time lucky.

[FrankGevaerts]

Getting really close now! I'm still surprised every time how much smaller those boards are than the breadboard build. I should be used to it by now...

[tinygriffy]

13:14 no, you don't ... would be interesting though to see you in lab coat and rubber gloves handling beakers with caustic substances etching motherboards .. or in the shop drilling and riveting 152 vias :D .. these board manufacturers made prototyping so easy for us, it's a bliss.
But it would be quite a sight i bet ... all your boards hand made in shiny copper with transparent solder mask...

[DustinWatts]

@03:58 An answer to your question might by; because the footprint has a standard prefix of U. Probably used a custom footprint? You can edit that footprint to have the default prefix of C. If you look up the footprint you are using in the library and click "Edit", on the left you can see under custom attributes something like "U?". If you change and change that to "C?" and save it, the next time you use the new saved footprint you will have it starting with C. Again, great progress! :)

[retrocomputeruser]

Not sure if this will help when connecting grounds together. I always leave the grounds unconnected then do an upper and lower ground fill after everything else which auto connects them where possible (It does in Kicad and EDA should). Any remaining unconnected grounds can usually be achieved with via's to both planes or a simple re-route of a Net.

[scottjcrouch]

As a complete novice, one of the things I've been surprised by while watching you develop your designs is the use of small delays with a few NOT gates to satisfy timing constraints. In the back of my mind it felt a bit "hacky" because my intuition was built upon operations always being aligned to a clock edge (so a theoretically perfect digital circuit could be clocked to arbitrary speeds, but introducing the concept of delays suddenly puts an upper bound on that). Is this technique something that you could expect to see in high-speed silicon?

[TomStorey]

Traces coming out of the side of the pads really triggers me 😄

[miege]

It is probably fixed by now, but just in case: the bit-7 output LED is the wrong way round 16:03

[twobob]

heart emoji. time for some more paste.

[AiOinc]

Please tell me you're going to convert the diode matrix into a something more elegant than the mess of jumpers on that premade board