INT 21 - Concurrent DOS v3.2+ - INSTALLATION CHECK
AX = 4451h
Return: CF set if not Concurrent DOS
AX = error code (see AH=59h)
CF clear if successful
AH = single-tasking/multitasking nature
10h single-tasking
AL = operating system version ID (see AX=4452h)
14h multitasking
AL = operating system version ID
32h Concurrent PC DOS 3.2
41h Concurrent DOS 4.1
50h Concurrent DOS/XM 5.0 or Concurrent DOS/386 1.1
60h Concurrent DOS/XM 6.0 or Concurrent DOS/386 2.0
62h Concurrent DOS/XM 6.2 or Concurrent DOS/386 3.0
66h DR Multiuser DOS 5.1
Notes:  as of Concurrent DOS/XM 5.0 (possibly earlier), the version is stored
in the environment variable VER
use this function if you are looking for multitasking capabilities,
AX=4452h for single-tasking
this function should never return the single-tasking values
SeeAlso: AX=4459h

See also: 214452

214451 - Concurrent DOS v3.2+ - INSTALLATION CHECK