Int 21 Fn 4452  - Dr Dos 3.41+ - Determine Dos Type/get Dr Dos Version     [O]

   AX = 4452h ("DR")
   CF set

Return: CF set if not DR DOS
       AX = error code (see #1366 at AH=59h/BX=0000h)
   CF clear if DR DOS
       AX = version code
       AH = single-user/multiuser nature (see #3761)
       10h single-user
           AL = operating system version ID (see #1267)
       14h multiuser
           AL = operating system version ID (see #1266)
       DX modified (refer to note below)

Notes: the DR DOS version is stored in the environment variable VER
   use this function if looking for single-user capabilities, AX=4451h
     if looking for multiuser; this call should never return multiuser
     values
   in DR DOS 3.41-6.0, DX=AX on return; for Novell DOS 7, DH=AH but DL=00h
     (reportedly, DH=00h when booting NWDOS7 from installation disks)
   Novell DOS 7 returns error code 0001h if SETVER x.255 is in effect for
     the calling program, or SETVER /G x.255 is in effect

See Also: AX=4412h,AX=4451h,AX=4459h

(Table 1267)
Values for Digital Research operating system version ID:
 41h   DOS Plus 1.2
 60h   DOS Plus 2.0 or 2.1
 63h   DR DOS 3.41
 64h   DR DOS 3.42
 65h   DR DOS 5.0
 67h   DR DOS 6.0
 70h   PalmDOS
 71h   DR DOS 6.0 March 1993 "business update"
 72h   Novell DOS 7.0
 73h   OpenDOS 7.02

See Also: #3761

Bitfields for CP/M type indicator:
Bit(s) Description (Table 3761)
 7-4   CPU type
   0000 = 8080
   0001 = 8086
 3-0   OS type
   0000 = CP/M
   0001 = MP/M
   0002 = CP/Net
   0004 = multiuser

See Also: #1267