4 ms·

You said general purpose, which X, Y, and SP most certainly are not. You can't do much math ops with X and Y; SP is even more restricted. If we're being more

You said general purpose, which X, Y, and SP most certainly are not. You can't do much math ops with X and Y; SP is even more restricted. If we're being more generous then EXP clearly wins over the 6502 because it has two registers that can be used interchangeably. T's only failing is its propensity for being overwritten by TEST. EXAs also have attached memory in the form of a file. Accessing that memory takes a "few" more cycles than it takes the 6502 to access the zero page. But it's there none the less.

boomlinde 8y ago
> You said general purpose, which X, Y, and SP most certainly are not. You can't do much math ops with X and Y; SP is even more restricted. In that sense I wouldn't say that the accumulator in 6502 is a general purpose register in the first place, since it's just as useless for addressing as the X and Y registers are for arithmetic and logic operations. Each register in the 6502 has a distinct (but often overlapping) set of available operations, and that you can do arithmetic with one of them doesn't mean that it's a general purpose register.