exp7

.CSEG
.ORG 0x10

MAIN:   MOV R31, 0x00
        MOV R30, 0xFF
        CALL PUSH_

        MOV R30, 0xAA
        CALL PUSH_
        CALL POP_
        BRN MAIN

PUSH_:  ST  R30, (R31)
        ADD R31, 0x01
        RET

POP_:   LD  R30, (R31)
        SUB R31, 0x01
        RET