~Page http://www.piclist.com/techref/microchip/math/bit/detchng.htm
Modified by:ADV--A41 snurple@hotmail.com
preview-to: 
Bob Ammerman says:
</PRE>
; compare register "last_inputs" to current PORTB reading
; 
; direct computation of ~last_inputs & new_value

    comf    last_inputs,W
    andwf  PORTB,W
    andlw  (1<<4)|(1<<5)
    skpz
    goto    got_a_0_to_1

<PRE>