Hi all! > > I know that this is a simple question which has no doubt been > > asked many times before, but I cannot understand or make any sense of the > > PCLATH in relation to look-up tables. > > It's fairly simple to understand, if you bear these simple rules in mind: > [note that when I refer to the top "byte" of the program counter or PCLATH, > I'm talking about bits 8-12; the top 3 bits are unimplemented]. > > [1] On the 16Cxx chips, PCLATH is never modified except under program > control. On reset, its value is undefined and you should make no > assumptions about it. Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on Power-on Reset Value on all other resets Bank 0 0Ah PCLATH - - - Write buffer for upper 5 bits of the PC (1) ---0 0000 ---0 0000