I built a RISC-V emulator that runs DOOM
Demo: https://www.youtube.com/watch?v=f5uygzEmdLw Hi HN, I built a RISC-V emulator that implements the RV32IM instruction set and a minimal syscall interface to run DOOM. A few weeks ago, I got my first output with a simple hello world assembly program. Since then I have been working tirelessly to get DOOM to run. I needed to figure out how to run C programs first, and came across newlib, which allows the underlying environment to implement the syscall stubs one by one until the programs run. I have also added ELF loading, but currently only a single `PT_LOAD` segment is…
In plain words
This is a RISC-V emulator that supports the RV32IM instruction set and runs the classic game DOOM. Built by an individual developer, it implements ELF loading and a minimal syscall interface using newlib to execute C programs. The emulator can render DOOM to a fixed memory area and demonstrates full compatibility with complex software beyond simple assembly programs.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
Demo: https://www.youtube.com/watch?v=f5uygzEmdLw Hi HN, I built a RISC-V emulator that implements the RV32IM instruction set and a minimal syscall interface to run DOOM. A few weeks ago, I got my first output with a simple hello world assembly program. Since then I have been working tirelessly to get DOOM to run. I needed to figure out how to run C programs first, and came across newlib, which allows the underlying environment to implement the syscall stubs one by one until the programs run. I have also added ELF loading, but currently only a single `PT_LOAD` segment is supported. To port DOOM, I used doomgeneric, which was quite convenient to get working once the required stubs were in place. DOOM renders to a fixed area in memory (0x705FDD = VRAM_START): 0x7FFFFF +-------------------------------------+ | | | QUEUE_SIZE (32 bytes) | | | 0x7FFFDF +-------------------------------------+ <-- QUEUE_START 0x7FFFDE | QUEUE_READ_IDX | 0x7FFFDD | QUEUE_WRITE_IDX | +-------------------------------------+ | | | | | VRAM (1,024,000 bytes) | | | | | 0x705FDD +-------------------------------------+ <-- STACK_START | Stack | | | | | v | | | | ^ | | | | | Program data + Heap | | | 0x000000 +-------------------------------------+ I made a small linker script so that the entry point of a C program is at _start and virtual address is always 0. That kept the ELF loader code simple. Inputs are written to the queue by rvcore which are then intercepted by DOOM running inside it.
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