>  I just finished my first interrupt routine for a PIC 16c74 and looked at
> p. 2-639 of the microntoller databook. They suggest a routine
> to save the current value of the STATUS and W register before
> procedding through the interrupt routine and restoring these values
> upon completion of the routine. What I don't understand is why
> they swap the nibbles of the status register. I would appreciate
> any advice.

It is probably not necessary to swap the nybbles of the status register
(though it doesn't hurt anything; "movf XX,w" takes just as long as
"swapf XX,w").  It is, however, necessary to swap the nybbles of the W
register (and the status may have been swapped for consistency).  If the
W register wasn't swapped, an attempt to reload it using a "movf XX,w"
would trash the status register.  By contrast, "swapf XX,w" does not have
this effect.

By the way, there are a couple of other approaches that could be used for
similar effect; I don't think anything would be any shorter than the
"swapf" approach, though, even though that approach does have one "waste"
instruction.