Alrightty then. . . If I wanted to write a byte to the display port without changing anything would this work. call $7F3 in a,(11h) ; I am not sure if this is legal or %0110000 ; what I want to do is to turn bytes 5,6 on and leave all the others as they are. I am not sure if this is right. Actually, it probably isn't. Is there a way to do this logically, or do you just do set 6 set 5. .