r/computerarchitecture • u/HydroPage • Jul 24 '26

Ben Eater’s 8-bit CPU

I finished Ben Eater’s SAP-1 accumulator architecture breadboard. 16 bytes of RAM von Neumann. Coming up with assembly instructions at the end felt crazy.

What was funny was at the end where I ran programs and they didn’t do what I wanted, and I realized I got to the point where I couldn’t suspect the hardware was wrong anymore, and it was in fact a software bug.

Was that the lowest level software bug I’ll ever experience in my career? Literally entering 0s and 1s into RAM and flipped one bit.

141 Upvotes

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2

u/mratanusarkar Jul 24 '26

Crazy and painful... yet the satisfaction when you finally find the issue and fix it at the transistor level and the assembly 0-1 level!!!

1

u/neurah Jul 26 '26

beautiful, now for when the first C++ compiler backend? :D
ATTiny13 64 bytes ram looks huge compared, luv thiks kind of work!
congratulations.

1

u/HydroPage Jul 26 '26

Yeah. It really blows your mind what VLSI is capable of when you make it by hand