Hi Michael,

You make a lot of good points but the fact is that the PIC already HAS an
instruction to subtract a literal from W: ADDLW. Just use ADDLW with the
two's complement of the literal you want to subtract. Most assemblers will
even handle it for you if you put a negative sign in front of the literal.
I use it all the time.

I don't know why Mchip called SUBLW by that name rather than SUBWL. I think
Andy Warren has something about that on his Fast Forward Engineering Answer
Page, and IIRC, it was a silly decision just to make it similar to the
other mnemonics (which end in LW).

Sean

At 10:16 PM 5/25/01 -0500, you wrote:
>The SUBLW instruction is another good example.  It would have been nice (and
>much more useful) had it actually been a "subtract literal from W"
>instruction but it's not.  It is a "subtract W from literal" instruction,
>regardless of the confusing mnemonic that was chosen.  Perhaps someone can
>explain to me why the mnemonic is inconsistent with the way the instruction
>works.  It's going take some strong arguments to convince me that it's
>better or cheaper or more efficient this way instead of having the mnemonic
>be SUBWL.  Perhaps someone can explain to me the necessity of CLRF and CLRW

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