Here it is, full 6502 & 6522 emulator on Scratch. If you edit the rom list, it should work. Do not change the 32765th and 32766th bytes or the reset vector will be different. Press r any time to reset the CPU. Press and hold a to step the clock manually. You can do that by pressing space while holding a. Here is the full opcode (I haven't implemented them all.): https://www.masswerk.at/6502/6502_instruction_set.html