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=A2h

See also: 21A0

21A1 - Attachmate Extra - SET 3270 DISPLAY STATE