I recently came across and emulator called cool nes here on scratch https://scratch.mit.edu/projects/561973653/ and was wondering what possible changes would need to be made to it to run other 6502 based consoles (Atari 2600, Commodore 64, ect) through it

the 6502 isn't the only thing that makes up an nes, so probably a lot

well i know that

the_sucram_dev wrote:

I recently came across and emulator called cool nes here on scratch https://scratch.mit.edu/projects/561973653/ and was wondering what possible changes would need to be made to it to run other 6502 based consoles (Atari 2600, Commodore 64, ect) through it

There has actually been an Apple I emulator that uses a different 6502 core but takes the same idea of reusing the core. There are some differences between the 6502s used in each machine (mainly with illegal opcodes), but in theory you could plug one core into another assuming you handle all the other bits of the machine, which is far from trivial.