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Unformatted text preview: of its users as a
complete programming environment, not just an operating system.
MS-DOS stands for Microsoft Disk Operating System. It is a single-user operating
system for IBM and IBM-compatible personal computers. It was introduced in
1981 jointly by Microsoft and IBM and was the most popular operating system for
personal computers in the 1980s. Its popularity started reducing in the 1990s with
the launch of Microsoft Windows operating system.
Structure of MS-DOS
MS-DOS is structured in the following three layers:
BIOS. BIOS stands for Basic Input Output System. It contains device
drivers for the standard devices such as keyboard, disk, floppy, printer, and display
monitor. It also contains the basic low-level services such as time-of-day and
system configuration analysis. Having the hardware-dependent services in BIOS
ensures that the other higher-level operating system services can be offered in a
hardware-independent manner, enabling those operating system services to be
easily portable to other machines.
The BIOS is usually supplied by the computer manufacturer, rather than by
Microsoft, and is generally located, in part, in a ROM, which is a non-erasable
memory. When the computer's power is switched on, control is transferred by
hardware to the bootstrap procedure of the BIOS in ROM. The bootstrap
procedure carries out some hardware tests to check whether the memory and other
hardware devices are functioning properly. If the hardware test passes
successfully, the bootstrap procedure loads into the memory a small portion of the
operating system from the disk. This part of the operating system then loads the
rest of the memory resident portions of the operating system into memory from the
disk. This step-by-step process of loading the operating system into memory is
known as booting the system.
2. Kernel. This layer contains all the modules for process management, memory
management, and file management. These modules are written in machineindependent manne...
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This document was uploaded on 04/07/2014.
- Spring '14