CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

4.1. What Is a Computer?

Computers are a major element of our society, and they exist in so many places that we tend to forget that they are there. In simple terms, all computers are made up of four basic functions:

• Data input

• Data output

• Processing

• Storage

These functions, along with their related devices, are illustrated in Figure 4-1. In this chapter, I briefly introduce each of these functions and devices, which are covered in depth in Book II, Book III, and Book VIII.

Figure 4.1. The major functions of the computer.

Although the packaging of these functions takes very different shapes, from personal digital assistants (PDAs) and digital video recorders (DVRs) to routers, laptops, and tower computers, they all share these functions at the most basic layer. The CompTIA A+ Certification exam focuses on the common arrangement of devices performing these four functions — typically called the personal computer — and not the more obscure arrangement of devices (such as the automobile engine idle controller). The rest of this chapter guides you through the major components in the personal computer.