Operating Systems

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The operating system provides several essential functions, including:

All computing devices run an operating system. For personal computers, the most popular operating systems are Microsoft’s Windows, Apple’s OS X, and different versions of Linux. Smartphones and tablets run operating systems as well, such as Apple’s iOS, Google’s Android, Microsoft’s Windows Mobile, and Blackberry.

Early personal-computer operating systems were simple by today’s standards; they did not provide multitasking and required the user to type commands to initiate an action. The amount of memory that early operating systems could handle was limited as well, making large programs impractical to run. The most popular of the early operating systems was IBM’s Disk Operating System, or DOS, which was actually developed for them by Microsoft.

In 1984, Apple introduced the Macintosh computer, featuring an operating system with a graphical user interface. Though not the first graphical operating system, it was the first one to find commercial success. In 1985, Microsoft released the first version of Windows. This version of Windows was not an operating system, but instead was an application that ran on top of the DOS operating system, providing a graphical environment. It was quite limited and had little commercial success. It was not until the 1990 release of Windows 3.0 that Microsoft found success with a graphical user interface. Because of the hold of IBM and IBM-compatible personal computers on business, it was not until Windows 3.0 was released that business users began using a graphical user interface, ushering us into the graphical-computing era. Since 1990, both Apple and Microsoft have released many new versions of their operating systems, with each release adding the ability to process more data at once and access more memory. Features such as multitasking, virtual memory, and voice input have become standard features of both operating systems.

A third personal-computer operating system family that is gaining in popularity is Linux (pronounced “linn-ex”). Linux is a version of the Unix operating system that runs on the personal computer. Unix is an operating system used primarily by scientists and engineers on larger minicomputers. These are very expensive computers, and software developer Linus Torvalds wanted to find a way to make Unix run on less expensive personal computers. Linux was the result. Linux has many variations and now powers a large percentage of web servers in the world. It is also an example of open-source software, a topic we will cover later in this chapter.

Figure 3.1 Linux logo (Copyright: Larry Ewing)