> Were you aware of the neat little opcodes that were built into the 6502? I
> don't have my list of them any more, but back in the KIM days, there were
> several lists in circulation. As I recall, one of them was a double load,
> i.e it loaded a value into both a register and the accumulator. I believe
> another loaded a register and pushed the value on the stack at the same
> time. Esoteric, for sure, but you never know . . .
Like SHIFT&OR (0F,1F,1B,...), ROL&AND (2F,3F,3B,...), LSR&XOR ($F,5F,5B,...),
ROR&ADD (6F,7F,7B,...) etc ... most are realy exotic and save only a second
instruction, but some could have been a big help, if they had been official
(like AND A,X and STORE, without changing A or X - saving up to 4 instructions,
or LOAD A&X, or AND MEM&X/MEM&Y). Some are more or less useles, like the STOP
(halts execution, only reset will wake up the CPU) or just longer NOPs (two and
tree cycles).
THe 65xx stuff is quite known, but what has been new to my ears are the
8085 'hidden' operations.
Gruss
H.
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HRK
Received on Sat Apr 17 1999 - 13:06:08 BST