Hi, Here could be the loop to make the BSOD: BSOD: ld b,40 BsodLoop: ld a,$1F out ($10),a ld a,$1C nop nop out ($10),a djnz BsodLoop WaitLoop: ei wKeyLoop: halt bcall(_getcsc) or a jr z,wKeyLoop ret Hope That work........ i didn't try because i don't want to burn my lcd.... My exams start the next week so i must need my calc :-) But it should work Xavier LaRue > James Lancaster