INT 21 - DESQview - INSTALLATION CHECK
AH = 2Bh
CX = 4445h ('DE')
DX = 5351h ('SQ')
AL = subfunction (DV v2.00+)
01h get version
Return: BX = version (BH = major, BL = minor)
Note: early copies of v2.00 return 0002h
02h get shadow buffer info, and start shadowing
Return: BH = rows in shadow buffer
BL = columns in shadow buffer
DX = segment of shadow buffer
04h get shadow buffer info
Return: BH = rows in shadow buffer
BL = columns in shadow buffer
DX = segment of shadow buffer
05h stop shadowing
Return: AL = FFh if DESQview not installed
Notes:  in DESQview v1.x, there were no subfunctions; this call only identified
whether or not DESQview was loaded.  DESQview v2.52 performs function
01h for all subfunction requests 0Ch and higher and appears to ignore
all lower-numbered functions not listed here.
DESQview versions 2.5x are part of DESQview/X v1.0x.
BUG:    subfunction 05h does not appear to work correctly in DESQview 2.52
SeeAlso: INT 10/AH=FFh,INT 15/AX=1024h,INT 15/AX=DE30h

See also: 10FE

212B - DESQview - INSTALLATION CHECK