CODE XOR 2 chkPS,
    AX POPx, BX POPx, AX BX XORxx, AX PUSHx, ;CODE
CODE NOT 1 chkPS,
    AX POPx, AX AX ORxx,
    IFNZ, AX -1 MOVxI, THEN, AX INCx, AX PUSHx,
;CODE
CODE + 2 chkPS,
    AX POPx, BX POPx, AX BX ADDxx, AX PUSHx, ;CODE
CODE - 2 chkPS,
    BX POPx, AX POPx, AX BX SUBxx, AX PUSHx, ;CODE
CODE * 2 chkPS,
    AX POPx, BX POPx,
    DX PUSHx, ( protect from MUL ) BX MULx, DX POPx,
    AX PUSHx,
;CODE