Humberto Bonasso <PICLIST@MITVMA.MIT.EDU> wrote:

> Thus for all the chips with a program boundary under 2K (as 16F84
> is), why to care for those stupid bits in PCLATH ? In Jim's case, if
> I have to perform a call or goto inside the int service routine,
> simply I can do it without the need of handling the bits in PCLATH
> and saving it for future restore. The call or goto instruction
> always jumps to the correct address and returning to the original
> address is guaranteed as well. I knew that care has to be taken only
> when performing computed goto in table read for page crossing
> handling.
>
> Am I missing something relevant with this issue ?

Humberto:

I may be misunderstanding your message, but I think you may be
missing one thing... You're correct about regular CALLs and GOTOs --
for the 2K and smaller devices, they work fine without any
manipulation of PCLATH -- but even on the small PICs, you have to
ensure that PCLATH is correct EVERY time you perform a computed GOTO,
not just when your table crosses a page boundary.

-Andy

=== Andrew Warren - fastfwd@ix.netcom.com
=== Fast Forward Engineering - Vista, California
=== http://www.geocities.com/SiliconValley/2499