Introducing UNIX and Linux

The Computing Environment

Overview
What is a Computer?
Hardware
      Processors
      Input Devices
      Output Devices
Software
      Input and Characters
            Control Characters
      Application Programs
            Programming Languages
      The Operating System
      System Administration
History of UNIX and Linux
Conventions
Summary

What is a Computer?

In very basic terms, there are essentially two kinds of "thing" involved in computing. There are things you can kick, actual bits of machinery that you can pick up and take away, including the computer itself, printers, screens and other physical devices (digital cameras, scanners, disk drives, CD drives, etc.), which are collectively and individually known as hardware Thus, hardware includes the devices you use to communicate with a computer system (such as the mouse, keyboard), the actual components that make up that system, and any other devices.

Unfortunately, the hardware won't work by itself and needs detailed instructions, or programs, to make it do what it should. In addition to the hardware, therefore, it is also necessary to have a set of programs that tell the hardware what to do. These programs, which refer to the actual instructions rather than the medium on which they are stored, are collectively known as software. Software is needed for the basic operation of computers (like the software that is the subject of this book, UNIX and Linux) as well as for the more common applications that you may already be familiar with, such as word-processing, spreadsheets, games, MP3 playing, and limitless other possibilities. By themselves, hardware and software are not enough to do the things we want of computers - it is the combination of hardware and software that enables effective use of modern computers.

Below, we describe the different kinds of hardware and software in a little more detail.