Hardware Reference
In-Depth Information
Figure 3.1
Relationship between the different layers of the operating system
(DOS and BIOS)
Origins of DOS
Most microcomputer operating systems can trace their origins to the original
control program for microprocessors (CP/M) developed by Garv Kildall as a
software development environment for the Intel 8080 microprocessor. In its
original form CP/M was supplied on an 8" IBM format floppy disk. CP/M
was subsequently extensively developed and marketed by Digital Research in a
variety of forms including those for use with Intel and Motorola microprocessor
families.
In the last 1970s, CP/M rapidly became the
de facto
operating system for most
8080, 8085, and Z80-based 8-bit microcomputer systems. However, with the
advent of 16-bit machines and the appearance of the IBM PC in 1981, a new and
more powerful operating system was required. Digital Research produced an
8086-based version of CP/M (known as CP/M86); however, Microsoft produced
a rival product (PC-DOS) which was adopted by IBM for use with the PC.
Microsoft quickly also developed an operating system (MS-DOS) for use with
PC-compatible machines. This operating system rapidly became the world's
most popular microcomputer operating system. Windows was later added to
the MS-DOS system in order to provide a more user-friendly graphical user
interface (GUI).
Note that if the system is not configured to boot into Windows on start-up
the user will normally be presented with the command line interface. This
text-based interface permits the entry of DOS commands and the execution
of programs by simply typing the executable filename at the DOS prompt. A
comparison of the way in which similar information is presented DOS and
Windows can be made from Figures 3.2 and 3.3.
The MS-DOS operating system can be configured for operation with a wide
variety of peripheral devices including various types of monitor, serial and
parallel printers, and modems. Each individual hardware configuration requires
its own particular I/O provision and this is achieved by means of a piece of
