i have been writing a gameboy emulator for the last year (with short bursts of work where i implement some module), and it's been very challanging and fun, i recommend everyone to try it.
it has a very simple 8-bit (risc) architecture, but obviously tailored for games (for example, it has a dedicated sprite memory sector). i recommend people to try it out because it is has fun quirks compared with "regular" architectures, like arm and x86, for example in the way it handles cartridges, or in that some cartridges actually had non-trivial logic inside them and weren't just a rom.
it always amazes me how active gameboy research and development is still today, for example there's a very recent gameboy emulator / research project done in rust https://github.com/Gekkio/mooneye-gb
there are even test roms with which you can test your emulator to see if it implements all opcodes, interrupts and whatnot correctly (where correctly not only means "with respect to the effects" but also with respect to how many cycles everything should take). example of these test roms: http://gbdev.gg8.se/files/roms/blargg-gb-tests/
also for example this disasm of pokemon red: https://github.com/pret/pokered
if you want to write an emulator or a game and you have basic computer organization knowledge, i'd start with the famous pandocs.
it has a very simple 8-bit (risc) architecture, but obviously tailored for games (for example, it has a dedicated sprite memory sector). i recommend people to try it out because it is has fun quirks compared with "regular" architectures, like arm and x86, for example in the way it handles cartridges, or in that some cartridges actually had non-trivial logic inside them and weren't just a rom.
it always amazes me how active gameboy research and development is still today, for example there's a very recent gameboy emulator / research project done in rust https://github.com/Gekkio/mooneye-gb
there are even test roms with which you can test your emulator to see if it implements all opcodes, interrupts and whatnot correctly (where correctly not only means "with respect to the effects" but also with respect to how many cycles everything should take). example of these test roms: http://gbdev.gg8.se/files/roms/blargg-gb-tests/
also for example this disasm of pokemon red: https://github.com/pret/pokered
if you want to write an emulator or a game and you have basic computer organization knowledge, i'd start with the famous pandocs.