"The SPC81A 8-bit microprocessor is a high performance processor equipped with Accumulator, Program Counter, X Register, Stack pointer and Processor Status Regi

"The SPC81A 8-bit microprocessor is a high performance processor equipped with Accumulator, Program Counter, X Register, Stack pointer and Processor Status Register (this is the same as the 6502 instruction structure)." Well not exactly haha. Yeah, if you look at the source code. No Y register related instructions! I thought about it and you could get used to writing code without the Y register pretty quickly... The actual instruction set manual for SunPlus 6502 CPUs (covers several but you can see the low end doesn't have Y instructions) https://www.manualslib.com/products/Sunplus-Cpu6502-8692958.html https://www.manualslib.com/products/Sunplus-Cpu6502-8692958....