- bit KBDSTRB ; clear keyboard strobe
- bit BUTN0 ; check if OpenApple is down
- bmi :+
- and #$7F ; If not down, then clear high bit
-: ldx #$00
+ bit KBDSTRB ; Clear keyboard strobe
+ .ifdef __APPLE2ENH__
+ bit BUTN0 ; Check if OpenApple is down
+ bmi done
+ .endif
+ and #$7F ; If not down, then clear high bit
+done: ldx #$00