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MS-DOS 8.0 was included with Windows ME. It included out-of-the-box support for FAT32.

Windows ME's version of MS-DOS is not directly accessible under normal conditions due to ME's lack of Real Mode support. It differs primarily from earlier versions in that both SMARTDRV and HIMEM.SYS are integrated into the DOS kernel, IO.SYS, which is now also compressed and automatically loads into the High Memory Area. As a result, XMS is always enabled and the DOS=HIGH parameter has no effect. It is also incompatible with EMM386 due to the integrated HIMEM.SYS being loaded into the High Memory Area with the kernel, resulting in freezes when the A20 gate is closed. MS-DOS 8.0 is also slightly more memory efficient than previous builds and faster in some circumstances, such as booting into Windows. Its SYS command also lacks features from previous versions.

There have been four observed versions of MS-DOS/IO.SYS 8:

  • The standard version used for booting Windows ME. This version has broken Real Mode support and will ignore commands saved in CONFIG.SYS and AUTOEXEC.BAT. Its only purpose is to boot Windows ME.
  • The Emergency Boot version intended for system recovery. Though CONFIG.SYS and AUTOEXEC.BAT function normally in this version, serial and parallel port functionality as well as harddrive booting are not supported. This version is also included with Windows XP to 8.1 hidden inside the included diskcopy.dll, with the only notable difference being the change to reported Windows version and removal of the 'Millennial' branding.
  • The installation CD version is used in installing ME and has features of both the previous two. It lacks support for booting off the internal harddrive like the Emergency Boot version but also automatically loads Windows like the standard version. It uniquely has a functional F8 menu with a 'Command prompt only' option, allowing you to interrupt the ME loading process to run the normal DOS command interpreter. A special version can also be found on the OEM CD in \tools\nettools\fac\ltools.dta, by opening ltools.dta as a cab file.
  • A patched version released by Microsoft as part of update 311561 to fix MS-DOS 8 improperly processing harddrive hardware errors. The patch carries over into the first and second version if it it applied.


Microsoft Operating System Versions
Microsoft Operating System Versions:

MS-DOS: QDOS | 1.0 | 2.0 | 2.1 | 2.11 | 3.0 | 3.1 | 3.2 | 3.21 | 3.3 | 3.3A | 3.31 | 4.0 | 4.01 | 4.01A | 5.0 | 5.0A | 6.0 | 6.2 | 6.21 | 6.22 | 7.0 | 7.1 | 8.0

Windows 1.x: 1.0 | 1.01 | 1.02 | 1.03 | 1.04

Windows 2.x: 2.0 | 2.01 | 2.1 | 2.2

Windows 3.x: 3.0 | 3.0A | 3.1 | 3.11 | 3.2

Windows for Workgroups 3.x: 3.1 | 3.11

Windows 9x: 95 | 98 | ME

Windows NT: 3.1 | 3.5 | 3.51 | 4.0 | 2000 | XP | 2003

Windows NT: Vista | Longhorn Server | Blackcomb Server

Windows NT: Windows 8 | Windows 10 | Windows 11

Windows CE: 1.0 | 1.1 | 2.0 | 2.1 | 2.11 | 2.12 | 3.0 | 4.0 | 4.1 | 4.2 | 5.0

Windows Embedded: NT | XP

Windows Mobile: 2003 | 5.0

Previous Windows Codenames: Janus | Snowball | Kato | Daytona | Chicago | Memphis | Millennium | Cairo | Odyssey | Neptune | Whistler | Longhorn | Blackcomb