Migrating from PIC16F1825 to PIC18F26Q10

Hi,
Memory organisation is somewhat different in PIC18...  microcontrollers from PIC16... devices. 
Memory organization is described in Memory organization chapter of the datasheet.
 
In PIC16 devices, each memory bank is 128 bytes, of which 12 are Core CPU registers,
20 are SFR registers, and 16 are Common RAM memory bytes that can be reached regardless of Bank selection.
But this only leave 80 bytes of general data memory RAM in each bank.
 
In PIC18 devices, each bank is a full 256 bytes, and with the extra Access bank bit in each instruction,
there is a total of 512 memory or register bytes that may be reached, without changing bank selection.
Of those, 40 core CPU registers are reached in access bank, as well as 120 other SFR registers in access bank.
Then there are 96 bytes of general RAM memory (from bank 0) that may be reached the same way.
 
If your program code is well-behaved, and always do banksel instruction for the register to be used next,
then none of this may matter, and you may probably ignore the access {,a}  bit in instructions.
    movf    register, w
    movwf   register
and other instructions that use W as accumulator, will probably work as you are used to.
Also literal instructions like:
    movlw  konstant;    will function as usual, they do not have the a bit anyway.
 
If you have code that speculate in using Common RAM without bank selection in PIC16,
then you may have to consider using the access bit.
Or if code use Core CPU registers without bank selection, then maybe the assembler may help you.
 
These differences are general for all PIC18 devices, not just the new __Q10 family,
so probably have been discussed in migration documents for other devices,
and in this forum before.
 
    Mysil