Writing a Game Boy Emulator in OCaml

Re:Writing a Game Boy Emulator in OCaml by toast0 on Wednesday January 12, 2022 @01:21PM (#29910797)

I've written somewhere around 1/3rd of a NES emulator. It does the CPU, and the backround half of the PPU, but not foreground sprites, sound, controllers, or running at decent speed ;)

Anyhow, I found the CPU part a lot of fun, and there's public domain test roms with expected registers after each instruction that you can use to test and confirm. Interaction with other hardware and emulation of that hardware gets a lot more challenging. The gameboy is certainly different than the NES, but I suspect there's a lot of similarity at the high level. It's certainly reasonable to stop (or pause, perhaps), when it stops being so fun, too.

I'm also not sure porting an emulator is going to give you the same understanding as writing one, but maybe.

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Re:Writing a Game Boy Emulator in OCaml by ltriant on Wednesday January 12, 2022 @06:09PM (#29914060)

I wrote a decently complete NES emulator[1], and the 6502 is definitely a fun CPU to emulate compared to other CPUs. The Z80-ish CPU in the Game Boy is not as fun, and as soon as you get into 68000 territory, it definitely stops being fun for a hobbyist.

Getting the graphics and sound in sync with the CPU is a lot more challenging if you're looking to support many games, but if you just want to play some of the super simple early NES games, like Donkey Kong, then you can get away with a lot of inaccuracies.

[1]: https://github.com/ltriant/nes

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