DiPDoT

I may have gone slightly overboard designing relay-computer memory cards 😀

I've finalized the PCB design for the new "stackable" memory cards, allowing the relay computer to support up to 128 bytes of memory. Fitting everything onto the existing PCB format definitely required some creative engineering 😉

For those of you who enjoy following the projects during the design and debugging stages, I've been posting weekly behind-the-scenes updates over on Patreon — including schematics, PCB designs, early video access, and extra technical deep-dives that don't always make it into the main videos.

There's also a 7-day free trial if you'd like to take a look around:
patreon.com/dipdot

And as always, thank you all for following along and supporting these wonderfully impractical computer projects!

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1 month ago | [YT] | 148

DiPDoT

Happy Sunday! Here's quick update on the capacitor memory project:

I'm taking some extra time on this project as I really need to ensure that the design is 100% before committing it to a PCB. And to save some space (and get more caps on the board) I'm testing out some smaller capacitors to see if they can hold a charge long enough to make this memory usable.

I've also redesigned the read/write circuit to introduce a small delay between the clearing and writing to the capacitors, and then combined all of the capacitor clearing through one relay instead of 8. The result so far is that I need only half of the relays in the original read/write circuits, so that means even more space for caps!!! 😬

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2 months ago | [YT] | 77

DiPDoT

Happy Sunday! Here's some teaser shots of the new capacitor memory project that I've been working on. It almost works...but there are still some gremlins so I just want to work those out before I post the next video.

The capacitors are each storing 1-bit, while the relays are used for addressing and controlling the read/write/clear of the capacitors, as well as performing a refresh during read operations.

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4 months ago | [YT] | 113

DiPDoT

This weekend I was exhibiting at VCF Montreal, which was an awesome experience! I brought along the relay computer and teletype, and I honestly didn’t know what to expect—but the response was incredible! People were stopping by all day with questions, stories, and just genuine curiosity about how this stuff works.

Getting to talk through the sounds of the relays clicking and why these machines mattered was such a fun experience. What really stood out is how engaged everyone was—whether they’ve worked with this tech before or were seeing it for the first time.

It was an amazing weekend, and I’m really grateful to everyone who took the time in the cold weather to come by and check out the show!
 
❤️ #VCFMontreal

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5 months ago | [YT] | 52

DiPDoT

Just a quick update on a few things I’m working on!

First up is the reverse engineering of the front panel microcode, which has grown a bit organically over the last few months. Now that I know the concept works, it’s time to turn it into something “official” — a proper schematic and PCB design so the whole thing can finally fit neatly into the new case.

The other thing on my bench is some experimentation with producing numeric output instead of just straight binary. There are ICs that make this pretty easy, but to stay true to the rest of the build I’m exploring a “relay-based” approach to doing the same job. Not sure if this idea will make it into REV 1 of the front panel, but it's fun to figure out nonetheless!

A few other things are also brewing in the background, like figuring out the Teletype communications, capacitor memory experiments, design revisions for the relay computer, and pondering some ideas for the next home-brew machine!

So many projects on the go...I need more workbenches! 😂

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7 months ago | [YT] | 56

DiPDoT

Super excited to see one of these packages show up again! Time to put on some good tunes, warm-up the soldering iron...and get to work!!!

8 months ago | [YT] | 19

DiPDoT

I'm attending the 2025 Midwest Vintage Computer Festival this weekend in Schaumburg, IL. What an absolutely incredible collection of technology that spans from the 1920s through to today. Where else can you see (and use!!) amazing vintage machines and talk with the passionate folks who have restored them to their original glory.

What a trip!!! ❤️#VCFMidwest

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9 months ago | [YT] | 21

DiPDoT

Happy Sunday, everyone! 

Just a quick update on the mysterious timing issue I was having on the front panel mock-up. In summary, I had to add a capacitor to the ADDRESS gating in order for things to work, but I wasn't sure why at the time. Well, turns out it wasn't so mysterious after all, but as always, it was...ahem...human error! 😅  

Originally, I had the timing for the program counter to release at the same time as the address switches. But this meant the possibility that the address switches would close the gate _before_ the program counter has a change to fully latch the value. So, I just needed to wire the program counter control line to the shorter timing pulse (the same as the Load Instruction register was using) and voila! ... no more capacitor needed on the address gates.

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10 months ago | [YT] | 33

DiPDoT

Happy Sunday Everyone!

Currently prototyping the instruction decoder and having a lot of fun trying to cram all of the instruction controller relays onto a single card plus the routes. I tried some different layouts but ended up with the very linear-looking one...just needs some LEDs and then it's off for manufacturing.

And I'd like to take a moment to send a huge THANK YOU to Paul Law for openly publishing his schematics - these have been such a help in building this board and computer overall. Paul Law is currently working on getting PI calculating on his relay computer, so check out his channel here: youtube.com/@paul80nd

Also, I've set a goal to have a new video out every 3 weeks...which means I need to get something out next weekend! Not sure if this instruction decoder/controller will be ready by then, but if not --- I'll publish a fun "Quick Clicks" episode that will tackle a very popular question about...speed.

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1 year ago (edited) | [YT] | 27

DiPDoT

Every time I see this on the front porch, I literally feel like a kid again!

1 year ago | [YT] | 18