MSDOS.SYS

Source: Wikipedia, the free encyclopedia.

MSDOS.SYS is a system file in MS-DOS and Windows 9x operating systems. In versions of MS-DOS from 1.1x through 6.22, the file comprises the MS-DOS

DOS BIOS IO.SYS as part of the boot procedure.[1]
In some OEM versions of MS-DOS, the file is named MSDOS.COM.

In

Windows ME (MS-DOS 8.0), the DOS kernel has been combined with the DOS BIOS into a single file, IO.SYS (aka WINBOOT.SYS[2]), while MSDOS.SYS became a plain text file containing boot configuration directives instead. If a WINBOOT.INI file exists, the system will retrieve these configuration directives from WINBOOT.INI rather than from MSDOS.SYS.[3]
When Windows 9x is installed over a preexisting DOS install, the Windows file may be temporarily named MSDOS.W40 for as long as Windows' dual-boot feature has booted the previous OS. Likewise, the MSDOS.SYS of the older system is named MSDOS.DOS for as long as Windows 9x is active.

Some DOS utilities expect the MSDOS.SYS file to have a minimal file size of at least 1 KB. This is the reason why a large dummy comment is typically found in the MSDOS.SYS configuration file since Windows 95.[nb 1][4][5][6]

By default, the file is located in the root directory of the bootable drive/partition (normally C:\ for hard disks) and has the hidden, read-only, and system file attributes set.

The MS-DOS derivative

Disk Control Program [de] (DCP) by the former East-German VEB Robotron used a DCDOS.SYS filename instead.[7][8]

uses the file KERNEL.SYS for the same purpose.

bootmgr
instead, as they have a different boot sequence.

See also

Notes

  1. ^ The dummy comment in unmodified copies of MSDOS.SYS explains these reasons explicitly:

    The following lines are required for compatibility with other programs. Do not remove them (MSDOS.SYS needs to be >1024 bytes).

References

  1. Sybex
    . pp. 68–69.
  2. ^ a b Paul, Matthias R. (1997-10-02) [1997-09-29]. "Caldera OpenDOS 7.01/7.02 Update Alpha 3 IBMBIO.COM - README.TXT and BOOT.TXT - A short description of how OpenDOS is booted". Archived from the original on 2003-10-04. Retrieved 2009-03-29. [1] (NB. Also has a few bits on how other DOSes are booted.)
  3. ^ "Windows Does Not Start Normally With Bootgui=1 in the Msdos.sys". 2.0. Microsoft. 2013-10-24. KB136416, Q136416. Retrieved 2015-08-20.
  4. ^ "Contents of the Windows MSDOS.SYS file". 1.4. Microsoft. 2007-01-19. KB118579, Q118579. Retrieved 2015-08-20.
  5. ^ "How to create an MSDOS.SYS file larger than 1024 bytes". 1.3. Microsoft. 2004-12-21. KB129998, D36528. Retrieved 2014-11-22.
  6. PC Magazine
    . pp. 222–230. Retrieved 2019-07-27.
  7. VEB Robotron-Projekt Dresden. 1988-01-29. C3013-0000-0 M3030, Textdiskette DCP1700 T1/2 C3010-9991-2M3020, Disk-Nr.: 5962 /88 ROBOTRON PROJEKT DRESDEN KA2 DD-DS 80*16*256. Archived
    (PDF) from the original on 2021-08-29. Retrieved 2021-12-03.
  8. ^ Kurth, Rüdiger; Groß, Martin; Hunger, Henry (2016-11-29) [2007]. "Betriebssystem DCP". www.robotrontechnik.de (in German). Archived from the original on 2019-04-03. Retrieved 2019-04-28.

External links

MSDOS.SYS in Windows 9x (95/98/ME):