DETAILS OF MS-DOS OS

In July 1980 IBM assigned Microsoft to develop a 16-bit operating system for the personal computer for the fee of 186,000 dollars. Although the company Digital Research of Gary Kildall allready had with CP/M 86 such a 16-bit version,but by circumstances no contract has been established with IBM. Microsoft did not have yet any operating system, Microsoft licensed CP/M from Digital Research in November 1977 for 50,000 dollars. Since Microsoft could not sell licenses, a corresponding agreement with the company Seattle Computer Products was reached for QDOS. QDOS is a 16-bit clone of CP/M and was finished by Tim Paterson in April 1980. At first Microsoft licensed QDOS for 25,000 dollars. After a licence agreement with IBM was signed, Bill Gates bought QDOS for 50,000 dollars in July 1981. How proved this was a very lucrative business. IBM delivered it on all IBM computers as PC DOS for the first time on the IBM 5150 PC, for all other ones the name MS-DOS was for OEM partner. MS DOS 1.0 consists of about 4,000 lines assembler code.

The command interpreter is integrated in the file command.com with the internal commands for MS-DOS. Together with the file io.sys for simple device routines like the access to the monitor, keyboard, fixed storage disks and interfaces as well as the booting code these form the base operating system. DOS works very hardware near.

MS-DOS was wide spread in 1982 when 50 companies licensed MS-DOS. Software and hardware manufacturers build on this binary standard at this time. In 1983, the success of the PC system was clear the desire for a graphical surface was rising. Microsoft corresponded to the trend and announced a graphical user interface named Windows in 1983. Many other systems lost her market relevance at this time. In 1984 the number of PC and MS-DOS resellers increased to over 200. IBM published the AT computer in August, this one should refine the market for personal computer with MS-DOS 3.0/3.1. MS-DOS is already spread worldwide on Intel x86 computers in 1985. The easy extendibility of the computer by numerous plug-in cards of third party manufacturers, relatively low acquisition costs and a strongly growing amount of applications was a reason for it.

1988 was MS-DOS established and had reached measured on the market share a monopoly in the DOS market. The number of the MS-DOS installations grew worldwide to about 60 million and surpassed all other systems with that amount. Almost every software company offered standard applications like word processing, calculation or also special solutions like measurement tools, CAD (Computer Aided Design) or image processing for MS-DOS. The PC manufacturers designed her systems compatible to MS-DOS except for few manufacturers.

MS-DOS 5.0 allows the use of the High Memory and Upper Memory Area for DOS itself, TSR programs and drivers. The most important new external commands in this version are DOSKEY, DOSSHELL, EDIT, EMM386 and LOADHIGH. UNDELETE can recover deleted files, UNFORMAT can undo the format of floppy disks. 2.88 mb floppy disk drives from IBM are now supported. The BASIC interpreter was improved in detail.

Field of Application
- booting system for storage media
- File management
- For single user systems only
- Network client (NetBEUI, IPX/SPX, TCP/IP)
- batch processing

Structure information
- 16-bit operating system, (formerly 8-bit)
- Single tasking
- command interpreter for internal and external commands
- external driver software imbedding for periphery devices possible

System environment
- minimum: 512 kbytes RAM, 5 mbyte harddisk storage (depends on version for full installation)
- FAT file system
- executable with every x86 compatible CPU
- low RAM and fixed storage disk needs

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