Imran Nazar recreated a JavaScript animation demo on 1982 hardware and wrote up every decision along the way: 6510 assembler, fixed-point math with no floating point available, a CPU bug turned into a cosine lookup. When he lands at 30fps, he can tell you exactly why without running it. It's very cool.
pg_6502 is a fully functional MOS 6502 emulator running in pure PostgreSQL - registers, memory, and all 151 opcodes implemented as stored procedures. It passes functional test suites. Could you load a Commodore 64 ROM into it? Probably. Should you? That's not our call. But someone's going to port DOOM into PostgreSQL eventually, and this is how it starts. Has anyone seen SkyNet around?