Category: other operating systems
INT 21 - DR DOS 3.41+ - DETERMINE DOS TYPE/GET DR DOS VERSION AX = 4452h ("DR") CF set Return: CF set if not DR DOS AX = error code (see #01680 at AH=59h/BX=0000h) CF clear if DR DOS AX = version code AH = single-user/multiuser nature (see #01581) 10h single-user AL = operating system version ID (see #01580) 14h multiuser AL = operating system version ID (see #01579) 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 although based on DR DOS, CCI Multiuser DOS 7.xx, IMS Multiuser DOS 7.x, and IMS REAL/32 7.50+ do not support this call With OpenDOS 7.02 BETA 2 and DR-OpenDOS 7.02+, the install check in most tools has been changed to run with both, AH=10h and AH=14h to support possible future "client side" multiuser releases of DR-DOS which may return 14h instead of 10h. Tools should also strip off the CP/Net bit before checking the kernel version. Often used version checks like >= 1070h are invalid, therefore, hence the AH and AL must be checked seperately. In DR DOS 3.31-6.0, and DR PalmDOS, DX=AX on return. For Novell DOS 7 - DR DOS 7.03 the DX value returned by this function is the same as the DX value returned by INT 21/AX=3306h, and represents the DOS revision (bits 7-0, currently always DL=00h) and the version flags (bits 15-8, with bit 12 = DOS in HMA, bit 11 = DOS in ROM) of the "patch_version" field in the PCM_HEADER structure in the IBMDOS.COM file. The version flags, however, are updated at runtime to reflect the actual system status, resulting, for example, in DH=10h for DOS in HMA, and DH=0 when booting Novell DOS 7 from installation disks. The operating system version ID represents the BDOS (Basic Disk Operating System) kernel version (of the DRBDOS.SYS aka IBMDOS.COM file), and the two nibbles can actually be read as CP/M version and sub-version, that is DR-DOS 7.03 (version code 1073h) is actually CP/M-86 version 7.3. Due to lost original patch sources from the backups, Caldera OpenDOS 7.01 merely represented Novell DOS 7 Update 10 with minor changes. For Caldera DR-OpenDOS 7.02, all the Novell DOS 7 patches up to including Update 15.2 have been re-incorporated into the system from other sources, while the missing patches for IBMBIO.COM were independently re-implemented by Matthias Paul in 07/1997-10/1997. Novell DOS 7 (since 1993-11-08), OpenDOS 7.01 and OpenDOS 7.02 BETA IBMDOS.COM return error code 0001h if SETVER x.255 is in effect for the calling program, or SETVER /G x.255 is in effect. Since Caldera DR-OpenDOS 7.02 the SHARE 2.05+ (1998-01-05) driver uses INT 21/AX=65A2h as an *additional* BDOS version check: If the "FUCASE char" function is functional on a DR-DOS BDOS kernel 72h+, SHARE assumes it is running on an OpenDOS 7.02 BETA 1 (73h) kernel (or later) even if the BDOS version returned by INT 21/AX=4452h would indicate an earlier issue of the kernel. Some 3rd party drivers (like HPFS_DOS.EXE) were hardwired to detect Novell DOS 7 only, and so the kernel version had to be patched back on such systems to allow such drivers to work properly. The BDOS version and DOS revision are stored in PCM_HEADER of the IBMDOS.COM file, see table XXXX below. However, this is no longer necessary with the introduction of the DR-DOS 7.02+ IBMDOS.COM (since 1998-01-10) and SETVER 1.01+ (since 1998-01-12) because they allow to fake BDOS versions as well as faking DOS versions. In /X mode, a set sub-version of y = 100..127 will be used as BDOS version instead (64h..7Fh), while the DOS revision will be used to report the DOS sub-version instead. For example, given a DOS revision of 0, SETVER 6.114 would be the proper value to fake Novell DOS 7 (114=72h) on a DR-DOS 7.02+ system, reporting a DOS version of "IBM" 6.00. Sub-versions 128..255 will completely disable this BDOS version check, and report a DOS sub- version of 0..127. This is to work around problems with possibly hostile programs, that try to detect DR-DOS to not run on this OS. Additional version check for 1072h kernels: At API level, there is no known way to distinguish Novell DOS 7 from OpenDOS 7.01, however, an IBMBIO.COM/IBMDOS.COM file date since 1997 and the existance of an environment variable %OS%=OPENDOS usually indicates an OpenDOS system (but not the other way around; some OpenDOS BETAs still used %OS%=NWDOS!). Additional version checks for 1073h kernels: A functional test of INT 21/AX=65A2h (see above for SHARE) can be used to distinguish OpenDOS 7.02 BETA 1 from the later (OpenDOS 7.02 BETA 2+ and) DR-OpenDOS 7.02 and DR-DOS 7.02 releases, which are both the same, except for the name change and minor bug fixes. Testing for the INT 21/AX=6601h/BX=0000h bug can be used to differentiate the original release of DR-DOS 7.02 from later 7.02 updates and DR-DOS 7.03. The DR DOS version is stored in the environment variable VER. SeeAlso: AX=4412h,AX=4451h,AX=4459h