2 ; Ullrich von Bassewitz, 07.08.1998
4 ; unsigned char revers (unsigned char onoff);
12 ldx #$00 ; Assume revers off
15 ldx #$80 ; Load on value
16 ldy #$00 ; Assume old value is zero
17 L1: lda RVS ; Load old value
18 stx RVS ; Set new value
19 beq L2 ; Jump if old value zero
20 iny ; Make old value = 1
21 L2: ldx #$00 ; Load high byte of result
22 tya ; Load low byte, set CC