>> You're absolutely right Olin. I'd forgotten that. The A/D registers
>> did indeed read back as I thought they should have been set.
>
> You probably read them back after you initialized the A-D converter,
> while your macro error caused the relevant bits to be reset immediately
> before you actually read the values:

Bill, pretty sure that's what must have happened. Unfortunately that part
of the file had been edited, but I just re-wrote the display loop and put an
XOR in it to turn ADCON0,6 off and on. The result flicks between 989
(Vref = Vcc) and 1023 (Vref = Vref+) 

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