doomacracy
doom on an fpga
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README.md

doomacracy #

title screen, captured from the VGA pins in the VHDL simulation

Doom on a Terasic DE1, running on a homemade RV32IM CPU written in VHDL. See spec.md for the memory map, registers and flash layout, and sw/README.md for the software and the emulator.

The majority of this project was done with llms as a what if question on whether this was even possible.

Build #

nix develop path:$PWD
make sw emu            # firmware, flash image, emulator
make run-emu           # title screen in build/frames/
make cpu-test          # CPU against ideal memory
make soc-test          # whole board in nvc with chip models
make soc-boot          # boot the real firmware in nvc and compare with the emulator
make rom               # adds back boot rom
make qar               # build/doomacracy.qar Quartus archive

The WAD is not bundled with the repo; put the shareware doom1.wad in wad/.

Running it on the board #

make qar builds build/doomacracy.qar, which also carries flash.bin and jtag_flash.tcl. In Quartus II 13.0 SP1:

  1. Restore the archive, compile, and program doomacracy.sof (JTAG mode, one device in the chain).

  2. Load the flash once, no Control Panel needed: put SW9 up, press KEY0 (HEX shows 1000), then from the project folder run

    quartus_stp -t jtag_flash.tcl flash.bin

    HEX then counts through 2000 (erase, can take a minute), 3xxx (program), 4000 (verify) and 600d, and the game boots.

  3. Put SW9 back down. From now on KEY0 just boots Doom.

Redo step 2 only when the firmware changes.

the canonical repo for this is hosted on tangled over at https://tangled.org/dunkirk.sh/doomacracy

© 2026-present Kieran Klukas