INT 21 - Attachmate Extra - SET 3270 DISPLAY STATE
        AH = A1h
        AL = set status byte
            bit  7  : 0=windowed, 1=enlarged
            bits 6-3: current screen profile number 0-9
            bits 2-0: active window number
                        0=PC, 1-4=host B-E, 5-6=notepad F-G
SeeAlso: AH=A0h,AH=A2h

.