I started out using the sample code from the piclist FAQ - Detecting bit
changes.

I was unable to get it to fit in a loop and work out for me, so this is what
I came up with.  It seems to be working fine.

Since this is my first project, I wanted to put this up for critique and if
it is fine, for the next newbie to find.

Pressing a button on RB4 will turn on a LED on RB5.  Releasing button turns
off.
__________________________

Scan_Keys:      movf    PORTB,w         ;
                    movwf       scratchpad      ;put PORTB in a temp register
                xorwf   keys,w          ;compare to last rounds winners
                btfsc   STATUS,Z        ;Z=0 if same
                return                  ;same - go back
                comf    keys,w          ;
                andwf   scratchpad,w            ;
                andlw   b'00010000'     ;only worried about the input of RB4
                btfss   STATUS,Z        ;
                goto    rb4on           ;
                goto    rb4off          ;

rb4on:
                call tenmsdlay          ;a 10 millisecond delay

                btfsc   PORTB,4         ;see if it is still running
                bsf     PORTB,5         ;yep - so set it
                btfsc   PORTB,4         ;needs work
                bsf     scratchpad,5    ;set bit in scratch too
                goto    sav_keys        ;pick up added activations

rb4off:
                bcf     PORTB,5         ;
                bcf     scratchpad,5    ;
                goto    sav_keys        ;pick up new port settings
sav_keys:
                movf    scratchpad,w            ;
                movwf   keys            ;store new keys
                return

____end of code snippet****

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