GARTHWILSON wrote:
BigDumbDinosaur wrote:
although I had suggested to Bruce to use a different way of describing the registers (e.g., SP for the stack pointer, not S). Most machine language monitors don't use single letters to refer to the "control" registers, such as PC and SP.
Did machine-language monitors move away from the standard in order to reserve the single letters like S for commands?
I don't recall any more. What I do recall is that MOS Technology used two-letter notation for all registers except the accumulator and index registers. The dot notation for those registers was something I recall seeing c. 1977, when I got a set of typewritten developer's docs from MOS. Ever since then, I have used
.A,
.X and
.Y for the "user" registers,
PC for the program counter,
SP for the stack pointer and
SR for the status register. With the 65C816, I continued on that path with
DB for the data bank,
DP for the direct page pointer and
PB for the program bank. The two letter mnemonics are unambiguous (in particular, using
K to represent
PB is odd, as
K could conceivably also mean
DB, since both registers store a ban
K value) .