4 ms·
what makes it harsher? Also I believe CP/M was originally designed for the i8080.
by ido 8y ago
what makes it harsher? Also I believe CP/M was originally designed for the i8080.
- flohofwoe 8y agoI guess it's about the 6502's more RISC-like philosophy, which made it a bit more cumbersome to program in assembly code (even though the resulting performance was mostly similar to the Z80 because the 6502 could do more things in fewer cycles). Even with the whole 'extended register set in the zero page', the 6502 didn't have convenient features like 16-bit math, memory block instructions, and even 8-bit math was less convenient (e.g. no separate add/adc, sub/sbc instructions, so you always had to clear the carry flag before a math operation etc...) But I think this didn't matter for porting the operating system CP/M itself to 6502, the actual problem was binary compatibility with applications, and the Z80 was backward compatible with the i8080 (as long as only documented instructions were used). I guess being compatible with the i8080 (and CP/M 'office software') was the whole point why the Z80 was even created (as an i8080 killer), and that it was as successful as it was.