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DOS, or MS-DOS, is an acronym for Microsoft Disk Operating System. DOS has been the most widely used operating system since it was first released in 1981. It was manufactured by Microsoft to be the standard operating system for IBM and IBM compatible computers with 8088 or 8086 microprocessors. DOS became so popular because it was distributed by many OEMs (original equipment manufacturers) and because of its close tie to IBM.

There were many versions of MS-DOS, and each came with new support and helpful features. DOS 1.0 came out in 1981 as the first operating system on an IBM PC. DOS 2.0 was released in 1983, with bug fixes, hard disks added, and support for UNIX-like hierarchical file structure. In 1984 DOS could use 1.2 MB floppies, larger hard disks, and Microsoft Networks was added. DOS 5.0 ran in the HMA (high memory area) and used drivers in the HMA, to leave more conventional memory for use by applications. This version implemented DOS shell, a graphical interface that was easier than the traditional command prompt and more user-friendly. The last DOS version before it became obsolete was 6.0. This had data compression, built in virus detection, and improved memory management. After the mid 90ís, DOS was not used as much when very advanced versions of Windows and UNIX were released.

There were many other operating systems built for computers. DOS 1.0 resembled CP/M, one of the very first operating systems. CP/M (Control Program for Microprocessors), was released by the Digital Research Corporation, but never became popular because it was not the standard operating system for IBM. Other operating systems are OS/2, UNIX, Linux, P-system, and XENIX. UNIX was made at Bell Laboratories in the late 1960ís for workstations, and had support for multi-users and multitasking. It was written in C by many engineers and students. UNIX was modular, assembled in separate pieces, so it was very flexible and popular to networked companies.



Microsoft MS-DOS Userís Guide and Reference

Upgrading and Repairing PCs by Scott Mueller

Advanced MSDOS by Ray Duncan

Grolierís Multimedia Encyclopedia 1997

Internet- Ask Jeeves