On Mon, 9 Mar 1998 16:58:02 +1000 TONY NIXON 54964
<Tony.nixon@ENG.MONASH.EDU.AU> writes:

>In a multi page ROM environment like the 'C74 you should always set
>the
>state of PCLATH<3> when addressing above or below the 2K boundary. It
>is this bit that creates a 12 bit address from the 11 bit address
>supplied in a
>GOTO/CALL instruction. If this bit = 0 you address under 2K. If
>this bit = 1 then you address 2K and over.


        And Microchip has defined a special instruction to handle this.
If you just say

        LCALL   MySubroutine


        MPASM will put in the appropriate BSF and BCF instructions on
PCLATH, then do a call.
        Easier than remembering which bit does what!  In adition, for
dealing with I/O and RAM, I've defined macros called bank0 and bank1.  I
don't have to remeber which bit handles that anymore either.

Harold


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