At 05:22 PM 5/6/98 -0400, you wrote:
>I'm trying to use the watchdog timer on a PIC16C63.
>
>How do I turn it on?
>
>So far I'm able to write to the options register as follows:
>
>movlw   b'00001111'   ; Program WDT to 128 * .018ms = 2.3 seconds
>movwf   81h
>
>Note: For some reason I couldn't write to OPTION, the assembler did not
>recognize this word.
>


While I was writing my first program using the 16F84 I encountered the same
problem. However, on reading David Bensons 'Easy PIC'N' I learnt that the
that the option register is refered to as a 'buried' register, meaning that
it is not included in the file register space, and having no address. As
such, to write to this register of the 16F84, the format is:

movlw   b'00001111'   ; Program WDT to 128 * .018ms = 2.3 seconds
option

Try this format and see if it's the same for the 16C63 also.