PROCESSOR 18F4550
#include <xc.inc>

PSECT mycode

    MOVLW   025H        ; W = 25H  (first 8-bit value)
    MOVWF   20H, a      ; store first value at 20H

    MOVLW   037H        ; W = 37H  (second 8-bit value)
    MOVWF   21H, a      ; store second value at 21H

    MOVF    20H, W, a   ; W = 25H
    ADDWF   21H, W, a   ; W = 25H + 37H = 5CH
    MOVWF   22H, a      ; store result at 22H

HERE:
    GOTO    HERE        ; stay here so the result can be observed
