Many thanks for the suggestion. At the moment I'm just verifying that the hardware works, and will (hopefully) be combining this code with some existing code for other functions, one of which has 4 pots on AN1, AN2, AN3 and AN4, so I'm really looking at setting up PORTA for a 50/50 split of analogue / digital when I come to migrating this all to a new PIC (18F4580) when my samples arrive