To set OP1 to a decimal value between 0-99: ld a,12 call _SetXXOP1 To set OP1 to a decimal value between 0-65535: ld hl,12 call _SetXXXXOP2 call _OP2ToOP1 To set A and DE to the value of OP1 (max value of 9999): call _ConvOP1 > How do i store any number into op1, such as 12? It doesn't matter what number, I just > want to know how. And how do I put OP1 into a register?