Category: DOS kernel
INT 21 - DOS 2+ - GET DOS VERSION
AH = 30h
---DOS 5+ ---
AL = what to return in BH
00h OEM number (see #01394)
01h version flag
Return: AL = major version number (00h if DOS 1.x)
AH = minor version number
BL:CX = 24-bit user serial number (most versions do not use this)
---if DOS <5 or AL=00h---
BH = MS-DOS OEM number (see #01394)
---if DOS 5+ and AL=01h---
BH = version flag
bit 3: DOS is in ROM
other: reserved (0)
Notes: the OS/2 v1.x Compatibility Box returns major version 0Ah (10)
the OS/2 v2.x Compatibility Box returns major version 14h (20)
OS/2 Warp 3.0 Virtual DOS Machines report v20.30; Warp 4 VDMs report
the Windows NT DOS box returns version 5.00, subject to SETVER
DOS 4.01 and 4.02 identify themselves as version 4.00; use
INT 21/AH=87h to distinguish between the original European MS-DOS 4.0
and the later PC-DOS 4.0x and MS-DOS 4.0x
IBM DOS 6.1 reports its version as 6.00; use the OEM number to
distinguish between MS-DOS 6.00 and IBM DOS 6.1 (there was never an
IBM DOS 6.0)
IBM's PC DOS 7 and Y2K updates report themselves as IBM 7.0 to be
distinguished from the MS-DOS 7.0 portion of Windows 95.
MS-DOS 6.21 reports its version as 6.20; version 6.22 returns the
Windows95 returns version 7.00 (the underlying MS-DOS), as did the
"Chicago" beta (reported in _Microsoft_Systems_Journal_,August 1994);
Windows95 OSR2 and OSR2.5 (OPK3) return MS version 7.10
DR DOS 5.0 and 6.0 report version 3.31; Novell DOS 7 reports IBM v6.00,
which some software displays as IBM DOS v6.10 (because of the version
mismatch in true IBM DOS, as mentioned above). The Novell DOS 7
SETVER.EXE has an undocumented option /G x.y which sets the "global"
DOS version returned by this function for all executables not given
a specific version number in SETVER to major version x and minor
Heiko Goeman's Advanced WinDOS 2.10/2.11/2.21 returns "IBM" DOS 5.00
(subject to SETVER) and serial number 0.
All versions of CCI Multiuser DOS up to "CCI Multiuser DOS 7.22 Gold"
as of 1997-02-10 report DOS 3.31.
DR DOS 3.31, 3.32, 3.33, 3.34, 3.35, 3.40, 3.41, 5.0, 6.0 and
DR PalmDOS/NetWare PalmDOS 1.0 report version 3.31;
DR DOS "Panther" BETA 1 and "StarTrek" report as 5.0.
Novell DOS 7, OpenDOS 7.01, DR-OpenDOS 7.02, DR-DOS 7.02, DR-DOS 7.03
all report themselves as IBM 6.00, which some software displays as
IBM DOS 6.10 (because of the version mismatch in true IBM DOS,
as mentioned above). Use INT 21/AX=4452h to distinguish the DR-DOS
family from PC DOS.
The Novell DOS 7 and OpenDOS 7.01 SETVER.EXE has an undocumented
option /G x.y which sets the "global" DOS version returned by this
function for all executables not given a specific version number in
SETVER to major version x >= 5 and minor version y = 0..254,
y = 255 is used to disable the BDOS version check at INT 21/AX=4452h.
A slightly modified option has been documented for DR-OpenDOS 7.02+:
in /X mode it now allows for x >= 1, while y >= 100 requires /X mode,
and y >= 128 is used to control advanced version control means now
DR-DOS 7.02+ IBMDOS.COM (since 1998-01-10) now recognizes optional
paths to filenames stored in the SETVER list. Previously such entries
were never found. This allows for a three staged model for SETVERed
highest priority = entry with path is matching.
middle priority = entry without path is matching.
lowest priority = use global version (SETVER /G).
The DR-DOS 7.02+ SETVER 1.01+ (1998-01-12) has also been enhanced to
allow DOS *and* BDOS version faking (see INT 21/AX=4452h): In /X mode,
setting a sub-version of y = 128..255 will be reported as 0..127 DOS
sub-version, sub-versions of y = 100..127 will instead be used to
report this value as BDOS version (64h..7Fh) via INT 21/AX=4452h, and
the DOS revision stored in PCM_HEADER in the IBMDOS.COM file will
be used to report the DOS sub-version (usually this holds 0, but it
can be patched to other values, see INT 21/AX=4452h !!!).
Note, that DR-DOS SHARE 2.05+ (1998-01-05) has relaxed version
checking, and will install on any DOS revision 0..127, as long as
run on a DR-DOS 72h+ kernel (formerly it was bound to a revision
byte of 0 only).
Under Novell DOS 7+, the SETVERing also affects the version number
WORD stored at offset +40h in each program's PSP (see #01378).
This holds true even for special sub-versions of 100..255
(see INT 21/AX=4452h).
generic MS-DOS 3.30, Compaq MS-DOS 3.31, and others identify themselves
as PC-DOS by returning OEM number 00h
the version returned under DOS 4.0x may be modified by entries in
the special program list (see #01662 at AH=52h); the version returned
under DOS 5+ may be modified by SETVER--use AX=3306h to get the true
SeeAlso: AX=3000h/BX=3000h,AX=3306h,AX=4452h,AH=87h,INT 15/AX=4900h
SeeAlso: AH=20h"S/DOS",INT 2F/AX=122Fh,INT 2F/AX=4010h,INT 2F/AX=4A33h
SeeAlso: INT 2F/AX=E002h