AFAIR there always was a dedicated command for comparing with zero - for all flavors of "comparison" - because it's quite easy to implement and happens sufficiently often (e.g. when decrementing down).

And this command would also be shorter in length, since it doesn't need to read a constant from memory to compare with. And shorter length will also add up to the speed gain.

Now even if you used the longer command to compare with 0, a good assembler could try to optimize (think constant folding) a "comparison to a constant 0" to the shorter and faster "zero-compare"

I learned several assemblers, mainly MOS 6502 and Motorola 68000, but that was too long ago to tell you now where I've experienced this and give the correct mnemonics.

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In reply to Re^2: I prefer my indexes to start at: by LanX
in thread I prefer my indexes to start at: by Arunbear

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