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CHAPTER 2
Page 36
Introducing Operating Systems
OPERATING SYSTEMS PAST AND PRESENT
An operating system (OS) is software that controls a computer. It manages hardware, runs
applications, provides an interface for users, and stores, retrieves, and manipulates files. In general,
you can think of an operating system as the middleman between applications and hardware,
between the user and hardware, and between the user and applications (see Figure 2-1).
Application
(Microsoft Word)
Operating system (Windows Vista)
Hardware
RAM
LE
CPU
ROM BIOS
Printer
SA
Hard drive
Figure 2-1 Users and applications depend on the OS to relate to all applications and hardware components
Courtesy: Course Technology/Cengage Learning
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Several applications might be installed on a computer to meet various user needs, but a computer really needs only one operating system. As a PC support technician, you should be aware
of the older and current operating systems and how these operating systems have evolved.
DOS (DISK OPERATING SYSTEM)
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In 1986, MS-DOS (also known as DOS) was introduced and quickly became the most
popular OS among IBM computers and IBM-compatible computers using the Intel 8086
processors. Figure 2-2 shows a computer screen using the DOS operating system. In those
days, all computer screens used text and no graphics. DOS is outdated as a viable option
for a desktop computer operating system today. However, you might occasionally encounter
a diagnostic utility used to fix the most stubborn hardware or software problem that is
booted from a floppy disk or CD that uses the DOS operating system.
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Figure 2-2 DOS provides a command-line prompt to receive user commands
Courtesy: Course Technology/Cengage Learning
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