MSDOS.SYS is a system file in

MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few op ...

and

Windows 9x Windows 9x is a generic term referring to a line of discontinued Microsoft Windows operating systems released from 1995 to 2000 and supported until 2006, which were based on the kernel introduced in Windows 95 and modified in succeeding version ...

operating systems. In versions of MS-DOS from 1.1x through 6.22, the file comprises the MS-DOS kernel and is responsible for file access and program management. MSDOS.SYS is loaded by the DOS BIOS IO.SYS as part of the

boot A boot is a type of footwear. Most boots mainly cover the foot and the ankle, while some also cover some part of the lower calf. Some boots extend up the leg, sometimes as far as the knee or even the hip. Most boots have a heel that is clearl ...

procedure. In some OEM versions of MS-DOS, the file is named MSDOS.COM. In

Windows 95 Windows 95 is a consumer-oriented operating system developed by Microsoft and the first of its Windows 9x family of operating systems, released to manufacturing on July 14, 1995, and generally to retail on August 24, 1995. Windows 95 merged ...

(MS-DOS 7.0) through

Windows ME Windows Me (Millennium Edition) is an operating system developed by Microsoft as part of its Windows 9x family of Microsoft Windows operating systems. It was the successor to Windows 98, and was released to manufacturing on June 19, 2000, and t ...

(MS-DOS 8.0), the DOS kernel has been combined with the DOS BIOS into a single file, IO.SYS (aka WINBOOT.SYS), while MSDOS.SYS became a

plain text In computing, plain text is a loose term for data (e.g. file contents) that represent only characters of readable material but not its graphical representation nor other objects ( floating-point numbers, images, etc.). It may also include a lim ...

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. 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. By default, the file is located in the

root directory In a Computing, computer file system, and primarily used in the Unix and Unix-like operating systems, the root directory is the first or top-most Directory (computing), directory in a hierarchy. It can be likened to the trunk of a Tree (data st ...

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 (DCP) by the former East-German VEB Robotron used a filename instead.

IBM PC DOS IBM PC DOS (an acronym for IBM Personal Computer Disk Operating System),Formally known as "The IBM Personal Computer DOS" from versions 1.0 through 3.30, as reported in those versions' respective COMMAND.COM outputs also known as PC DOS or IBM ...

as well as

DR-DOS DR-DOS is a disk operating system for IBM PC compatibles, originally developed by Gary A. Kildall's Digital Research, Inc. and derived from Concurrent PC DOS 6.0, which was an advanced successor of CP/M-86. Upon its introduction in 198 ...

since 5.0 (with the exception of DR-DOS 7.06) used the file IBMDOS.COM for the same purpose, whereas DR DOS 3.31 to 3.41 used DRBDOS.SYS instead.

FreeDOS FreeDOS (formerly PD-DOS) is a free software operating system for IBM PC compatible computers. It intends to provide a complete MS-DOS-compatible environment for running Legacy system, legacy software and supporting embedded systems. FreeDOS ca ...

uses the file KERNEL.SYS for the same purpose.

Windows NT Windows NT is a Proprietary software, proprietary Graphical user interface, graphical operating system produced by Microsoft as part of its Windows product line, the first version of which, Windows NT 3.1, was released on July 27, 1993. Original ...

-based operating systems (NT 3.1–4, 2000, XP, and 2003) use the

NTLDR NTLDR (abbreviation of ''NT loader'') is the boot loader for all releases of Windows NT operating system from 1993 with the release of Windows NT 3.1 up until Windows XP and Windows Server 2003. From Windows Vista onwards it was replaced by the B ...

file and NT 6+ operating systems (Vista, 2008, 7, 8, 8.1, 10 and 11) use bootmgr instead, as they have a different boot sequence.

Notes

References

External links

MSDOS.SYS in Windows 9x (95/98/ME): * Microsoft Knowledge Base (MSKB)
List of MSDOS.SYS articles
* MDGx

* UKT Support

* Computer Hope

* MDGx

{{DOS system files DOS kernel DOS files DOS configuration files

See also

Notes

References

External links