Digital Logic Sim

Zhatt · 2025-04-29T21:37:34Z

The "ZHT80" is my project computer I've been building as I follow along Sebastian's and Ben's video series. So far it is essentially the same as Ben's 8-bit breadboard computer, but with my own solution for instruction memory and lookup. I'm trying to keep the design as clear and understandable as possible while still keeping it compact. I'm also minimizing the number of nested layers inside chips so its easy to see what is going on internally. As I'm not a programmer, I built a instruction compiler in Google Sheets. I can set the micro instructions then copy the export column into the micro instruction ROM. I'm still figuring out how I can add flag bits to this spreadsheet without making it overly complicated. Once I set up more instructions I'll create a program compiler in another tab. Things I still plan to add: Flag register and flag instructions (Turing complete) Instruction compiler spreadsheet Error message on display Keypad for manual entry Signed integers (the display has a toggle, but it's not connected) Dot display I'm considering reducing the micro steps from 5 to 4. That would make processing quicker and give me room for more instructions, but would require adding explicit instructions for moving data between registers. I'm not sure which would be more efficient ultimately. Once I add flags and ram, I'll record a video for Seb's playlist. I can also share the spreadsheet and project files.

A minimalistic digital logic simulator · By Sebastian Lague

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"ZHT80" 8-bit Computer

A topic by Zhatt created Apr 29, 2025 Views: 622 Replies: 6

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Zhatt167 days ago (1 edit)

I have given my computer a rework and am coaxing it to play pong. Check out the video:

The major elements done, but I'd like to add some flair to it, such some sort of graphic shown when you score, and score keeping. The issue is I'm running on the edge of speed for what is playable. Adding too much more will make it too slow.

Once I've added a few more features and cleaned up the wiring, I'll give a proper video tour.

Sebastian LagueDeveloper167 days ago

That's looking great, really cool work! If you want to upload the latest files, I'd be interested in using it as a test case for some optimizations.

Zhatt167 days ago

Thanks! I've emailed you the project files directly. I'd like to add a few more features and clean it up before I release it publicly.

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Digital Logic Sim

"ZHT80" 8-bit Computer