Introduction to Computing

What is a computer?

Before we can really talk about Java, we need to introduce some terminology. Sometimes when people speak of computers, they really mean a computing system: the computer itself, or hardware, and the programs, or software, necessary to perform desired tasks. Discussing each aspect separately is somewhat difficult, as they are so interrelated. A computer can do nothing useful without a program, and a program by itself is like an ignored list of directions.

Even so, we begin with a description of the computer as a machine. The hardware of a computing system includes not only the computer but also peripheral components such as:

• Printers
• Displays, and
• Scanners

We will treat these peripherals as a part of the computer.

What can a computer do?

Computers can perform astounding tasks, or so it seems. Actually, any major task is the result of many simple, basic operations. Just how rudimentary these operations are may surprise you! For example, a computer can:

• Get data from the outside world via a keyboard, a mouse, a disc, a scanner, the Internet, and so on.
• Save data, either temporarily or more permanently.
• Retrieve data that has been saved.
• Add, subtract, multiply, or divide two numbers.
• Compare two values to see whether one is less than, greater than, or equal to another.
• Manipulate data by either breaking it into pieces, joining it to other data, or moving it around.
• Display numbers, words, and other marks on a screen or on paper in various colors.

By performing these simple operations with great speed and accuracy, a computer can achieve impressive results.

The components of a typical computer

A typical computer has these major components, as the figure given below illustrates:

• Memory
• Input and output system
• Central processing unit

The connections between the various components are collectively called a bus.