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MS-DOS 5.0 - 6.x

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MS-DOS 1.x - 3.x

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MS-DOS 5.0 - 6.x

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Windows 98 & 98 SE

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MS-DOS 5.0 was released in 1991 with the following major additions: the ability to run DOS in the high memory area (HMA, a small area of memory resident above 1024 KB) and load some device drivers and programs in upper memory (a small area of memory intended for use by system hardware), the UNFORMAT and UNDELETE commands, MS-DOS Editor, QBasic, the ability to access more than two hard drives, and online help.¹⁴  The ability to run DOS in high memory and load some drivers and programs in upper memory was important because at the time, many DOS programs were designed to use only the first 640 KB of memory in a computer, known as conventional memory. Normally DOS uses some of that memory for itself, as do the drivers and programs that are required to be loaded on startup. If DOS and the required drivers can be loaded into another area of memory, there will be more conventional memory free for other programs. The UNFORMAT and UNDELETE commands allow the user to undo a disk format operation and recover deleted files. MS-DOS Editor is a simple text editor that makes an easy task of creating and editing text files, and QBasic is a new version of the BASIC programming language that replaced the version called GW-BASIC that shipped with earlier versions of MS-DOS. The ability to access more than two hard drives allows people to take advantage of the low cost of hard drives and install several in one computer (the prices began falling at an increasing rate near the time of MS-DOS 5.0's release). Online help in MS-DOS 5.0 provides documentation for all of the DOS commands and utilities.

Introduced in 1993, MS-DOS 6.0 provides several new utilities and features. Some of the most important are MSD (Microsoft Diagnostics), DoubleSpace disk compression, the Defrag utility, and Microsoft Anti-Virus.³  MSD supplies information about the computer's configuration, and is useful for troubleshooting. DoubleSpace allows the user to compress the data on hard drives and floppy disks, providing up to twice as much disk space. However, it does this at the expense of system performance, and many people reported problems with DoubleSpace, such as corrupt data or failed hard drives. The Defrag utility rearranges the files on a hard drive to improve performance, a process known as defragmenting. Microsoft Anti-Virus is a simple program for detecting viruses on a computer. For a while, regular updates were available to increase the number of viruses the program could recognize (known as virus definitions).

MS-DOS 6.2 was also released in 1993.³⁰  In addition to some minor changes, it added Scandisk, a utility to find and correct disk errors, and DoubleGuard, which protects against the data corruption that occurred with DoubleSpace in MS-DOS 6.0.²⁷  In 1994, MS-DOS 6.21 was distributed with DoubleSpace removed due to a lawsuit by Stac Electronics involving licensing issues with their Stacker program. The same year, MS-DOS 6.22 introduced a new drive compression program, DriveSpace.²⁸

©2001 Joe Hodsdon.  Page last updated