INT 21 - Attachmate Extra - GET 3270 DISPLAY STATE
AH = A0h
Return: AL = display status
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
BX = host window status
bit 15:  reserved
bit 14:  0=host E window installed, 1=not
bit 13:  0=host E terminal on, 1=off
bit 12:  0=host E window displayed, 1=not
bit 11:  reserved
bit 10:  0=host D window installed, 1=not
bit  9:  0=host D terminal on, 1=off
bit  8:  0=host D window displayed, 1=not
bit  7:  reserved
bit  6:  0=host C window installed, 1=not
bit  5:  0=host C terminal on, 1=off
bit  4:  0=host C window displayed, 1=not
bit  3:  reserved
bit  2:  0=host B window installed, 1=not
bit  1:  0=host B terminal on, 1=off
bit  0:  0=host B window displayed, 1=not
Note:   Attachmate Extra is a 3270 emulator by Attachmate Corporation

See also: 21A1

21A0 - Attachmate Extra - GET 3270 DISPLAY STATE