corn used super hle as i call it
basically very very high level emulation where the software gave the rom what IT and IT alone wanted... which meant each slight hardware call had to be coded round, so you can acheive good framerates... but compatibilty is very limited
youre newer emulators (nemu and later...) use a sort of lle whereby they actually emulate the hardware instructions, which the roms then access as they would the n64... which means theres a helluva lot more work going on but you get far better results in the end because when you get the hardware simulated in theory most roms should run on it, unless you forget something
