Tried this: 1010 DATA B6,50,00 ' LDA $5000 1020 DATA 8B,01 ' ADDA 1 1030 DATA 1F,A9 ' TFR CC,B 1040 DATA F7,50,01 ' STB $5001 1050 DATA B7,50,00 ' STA $5000 1060 DATA 39 ' RTS But gets strange behaviour in XRoar. Now i try to use STD EDIT: It the 1030 DATA 1F,A9 ' TFR CC,B what brings XRoar into tr...