MS-DOS 4

Not to be confused with the multitasking MS-DOS 4, a separate version released by Microsoft to a limited number of OEMs in 1986.

MS-DOS 4

Version of MS-DOS
Version	4.0
Preliminary name	MS-DOS 3.40
Release date	1988-07
Replaces
MS-DOS 3
Replaced by
MS-DOS 5

MS-DOS 4 is a version of MS-DOS released in 1988. This is the only version of DOS to be developed primarily by IBM prior to the collapse of the Microsoft–IBM collaboration. It includes significant improvements to the user experience, such as a full screen installation wizard, and the MS-DOS Shell. Support for drives larger than 32 MB has been added (although already implemented in previous versions by some OEMs), allowing partitions with sizes up to the FAT16 limit of 2 GB. MS-DOS 4 also includes EMM386, a memory manager that leverages features of the i386 processor to grant access to memory beyond the first megabyte addressable in real mode.

The original version, MS-DOS 4.00, was released in July 1988, had a short shelf life and is quite rare nowadays. It was replaced by MS-DOS 4.01 in November 1988 due to 2 major bugs both in the shell and the memory manager. There is also a separate version of MS-DOS, also version 4.0, that was developed by Microsoft between 1983 and 1986 and supports pre-emptive multitasking, but is completely unrelated to this version.

New features and changes

• Support for EGA and VGA display adapters.
• Support for FAT16 partitions larger than 32 MB.
• Support for the LIM / EMS standard (driver EMM386.SYS, access to additional memory on 386-based systems and higher), which allowed individual parts of the operating system to load into additional memory.
• Drastic improvements in functionality with the Select installation program. It now automatically creates the appropriate CONFIG.SYS and AUTOEXEC.BAT files.
• The introduction of a new MEM command, which allows users to analyze the current memory configuration.
• Four countries were added in the list of supported regions.
• Graphic printing was added.
• Various new features in existing commands, which includes: TREE, DELETE, MODE, APPEND, FASTOPEN, NLSPUNC, ATTRIB, FDISK, REPLACE, BACKUP, GRAFTABL, SELECT, COUNTRY, GRAPHICS.
• Improved system drivers, including: ANSI.SYS, DRIVER.SYS, DISPLAY.SYS, PRINTER.SYS.
• MS-DOS Shell was added.
• The SELECT program for setting up DOS on a hard disk has been transformed into a full-fledged setup wizard. Keyboard layout and install directory are now specified inside of the wizard rather than as parameters specified for SELECT.

History

The project started in early 1987 and was initially named "MS-DOS 3.40", and under this name was first mentioned in a contract between Microsoft and Zenith Data Systems from August 1987.

MS-DOS 4.00 was released in July 1988, only to be replaced by MS-DOS 4.01 in November 1988 due to major bugs in the shell and in the memory management system.

MS-DOS 4.02 was mentioned in a Microsoft document dated 2 July 1990, however, it is still yet to be found. According to the document, this version can’t be read by the IBM 3363 optical drive.

Source code

The source code for MS-DOS 4.00 was released under the permissive MIT license on 25 April 2024. It also contains toolkit and compiler set, with which it's possible to compile the source code. However, compilation may cause minor errors, due to files conversion from DOS to Unix format, missing variables and etc.

List of known OEM releases

MS-DOS 4.00

• RM Nimbus
• Sampo

MS-DOS 4.01

• AGI
• Amstrad
• AST
• Bondwell
• Emerson
• EPSON
• HP
• Inves
• Mitac
• Olivetti
• Packard Bell
• Philips
• Phoenix
• RM Nimbus
• Sharp
• Trigem
• Tulip
• Twinhead
• VEGAS
• Zenith

MS-DOS 4.01a

• Nokia
• Victor

MS-DOS 4.01d

• Compaq

Gallery

MS-DOS 4.00

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  Setup

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  DOSSHELL

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  MS-DOS 4.00

MS-DOS 4.01

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  MS-DOS 4.01