Running Doom on Our Custom CPU and Going Viral

Cool, I thought this was a CPU custom designed for Doom, but I guess that's just a 486 :)

edit: I went to down a quick hole "The historical footnote is that a version of this genuinely happened. SNES Doom shipped with a Super FX 2 in the cartridge, a custom RISC chip with a pixel-plot instruction, because the console's own CPU had no chance. Jaguar and PlayStation ports both moved the rasteriser onto dedicated hardware. Doom's design was shaped by the absence of an FPU, and then hardware kept getting built to catch up with it."

Reading "Custom CPU" I expected wafer.space, instead of FPGA.

Great work!

This reminded me of a project I built a while back: a RV32IM emulator in C++ that can boot and run DOOM. Initially I implemented only RV32I, and implementing the M extension provided a massive speedup!

If anyone's curious, here's the source code: https://github.com/lalitshankarch/rvcore

Very cool!

I just did the same thing, but for a byte-code interpreter for a completely novel ISA I made up a while back (with an assist from Claude). I just haven't made the HN post yet, since I'm doing a bit of cleanup.

https://github.com/paulmooreparks/Maize/

For anyone else curious: custom FPGA-based CPU code but not a custom architecture. This is an RV32I core. The article takes along time to give up this fact.

why Zmmul and not full M — is it just fpga area, or did the doom port let you drop div/rem?

Always a delight seeing Chisel in the wild :)

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