Page 14 - DCAP103_Principle of operating system

Unit 1: Operating System

Development of the single-chip microprocessor was an enormous catalyst to the popularization Notes
of cheap, easy to use, and truly personal computers. Arguably the first true “personal computer”
was the Altair 8800, which brought affordable computing to an admittedly select market in the
1970s. However, it was arguably this computer that spawned the development of both Apple
Computer as well as Microsoft, spawning the Altair BASIC programming language interpreter,
Microsoft’s first product. The first generation of microcomputers (computers based on a
microprocessor) that appeared in the mid-1970s, due to success of the Steve Wozniak-designed
Apple Computer release, the Apple II, were usually known as home computers. These were
less capable and in some ways less versatile than large business computers of the day.
They were generally used by computer enthusiasts for learning to program, running simple
office/productivity applications, electronics interfacing, and general hobbyist pursuits.
It was the launch of the VisiCalc spreadsheet, initially for the Apple II (and later for the
Atari 8-bit family, Commodore PET, and IBM PC) that became the “killer app” that turned
the microcomputer into a business tool. This was followed by the August 1981 release of
the IBM PC which would revolutionize the computer market. The Lotus 1-2-3, a combined
spreadsheet (partly based on VisiCalc), presentation graphics, and simple database application,
would become the PC’s own killer app. Good word processor programs would also appear for
many home computers, in particular the introduction of Microsoft Word for the Apple Macintosh
in 1985 (while earlier versions of Word had been created for the PC, it became popular initially
through the Macintosh).

In the January 3, 1983 issue of Times magazine the personal computer was named the “Machine
of the Year” or its Person of the Year for 1982. During the 1990s, the power of personal computers
increased radically, blurring the formerly sharp distinction between personal computers and
multiuser computers such as mainframes. Today higher-end computers often distinguish
themselves from personal computers by greater reliability or greater ability to multitask, rather
than by brute CPU ability.

1.2.1 Uses

Personal computers are normally operated by one user at a time to perform such general purpose
tasks as word processing, internet browsing, e-mail and other digital messaging, multimedia
playback, video game play, computer programming, etc. Other more specific functions usually
performed with the help of a PC include working, teleworking, learning, researching, printing,
online banking, online shopping and dealing online with public sector institutions and services.
The user of a modern personal computer may have significant knowledge of the operating
environment and application programs, but is not necessarily interested in programming or
even able to write programs for the computer. Therefore, most software written primarily for
personal computers tends to be designed with simplicity of use, or “user-friendliness” in mind.
However, the software industry continuously provide a wide range of new products for use in
personal computers, targeted at both the expert and the non-expert user.

1.3 Operating System Meaning

An operating system is an important part of almost every computer system. A computer system
can be divided roughly into four components: the hardware, the operating system, the application
programs, and the users (Figure 1.3).

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