DEC DEC Decrement memory by one DEC Operation: M - 1 -> M N V - B D I Z C / . . . . . / . +----------------+-----------------------+---------+---------+----------+ | Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles| +----------------+-----------------------+---------+---------+----------+ | ZeroPage | DEC $FF | $C6 | 2 | 5 | | ZeroPage,X | DEC $FF,X | $D6 | 2 | 6 | | Absolute | DEC $FFFF | $CE | 3 | 6 | | Absolute,X | DEC $FFFF,X | $DE | 3 | 7 | +----------------+-----------------------+---------+---------+----------+ For penalty cycles on the 65816, check the desired addressing mode. 65816 Extensions: +----------------+-----------------------+---------+---------+----------+ | Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles| +----------------+-----------------------+---------+---------+----------+ | Implied | DEC | $3A | 1 | 2 | +----------------+-----------------------+---------+---------+----------+ |