INTRODUCTION

What is a Microcomputer?

A microcomputer is a digital electronic computer designed for use by a single person. These were the first computers to have their CPUs on a single micro chip (hence the name). They are also called personal computers because of their intended use for typical personal activities such as writing letters, browsing the web, playing games, balancing a checkbook, etc.

Note that the term PC comes from “Personal Computer,” but the term “PC” is commonly used to refer specifically to microcomputers that use a system architecture descended from the IBM Personal Computer. Therefore, even though an Apple Macintosh microcomputer is also a personal computer, most people would not refer to it as a “PC.”

You may have noticed that I used several terms in the first paragraph to define “microcomputer” which only beg additional questions such as “What is a digital electronic computer?” and “What is a CPU?” Read on, and we will define these terms later in this tutorial!

What is a Computer?

The machine you think of as a “computer” is more precisely called a “general-purpose digital electronic computer.” It is general-purpose because it can be programmed to perform a wide variety of applications (making it different from a special-purpose computer designed to perform only one function). Digital means that computer handles all data internally in the form of numbers (all of the numeric data, all of the text data, and even sounds and pictures are stored as numbers). The word digit originally meant “finger” or “toe” and since people started counting on their fingers, the word digit also came to be applied to numbers. A different type of computer that represents values as voltage levels is called an analog computer, but you are unlikely to ever run into such a thing. Modern computers are all electronic because they manipulate data using electronic switching circuits (some older computing machines, or ideas for computers, were mechanical, using wheels, levers, etc. to perform calculations). A computer is a device that performs four functions: it inputs data (getting information into the machine); it stores data (holding the information before and after processing); it processes data (performing prescribed mathematical and logical operations on the information at high speed); and it outputs data (sending the results out to the user via some display method).
A computer system consists of both hardware and software. The hardware is the physical equipment: the computer itself, and the peripherals connected to it. The peripherals are any devices attached to the computer for purposes of input, output, and storage of data (such as a keyboard, monitor display, or external hard disk). The software consists of the programs and associated data (information) stored in the computer. A program is a set of instructions that the computer follows to manipulate data. Being able to run different programs is the source of a computer’s versatility. Without programs, a computer is just a lot of high-tech hardware that doesn’t do anything. But with the detailed, step-by-step instructions of the program (painstakingly written by humans) the computer can be used for tasks ranging from word processing a letter to Aunt Mary, to simulating global weather patterns. The computer appears to be so amazing simply because it can execute these sets of instruction very very fast; but it’s just following the program steps one by one in a very simple-minded manner.
As a user, you will interact with the programs running on your computer through the input devices connected to it, such as a mouse and a keyboard. You use these devices to provide input (such as the text of a report you are working on) and also to give commands to the program (such as specifying what text is to appear with bold formatting). The computer program will provide output (the data resulting from the manipulations within the computer) via various output devices for presenting the information (such as a monitor, a printer, or a sound output system that beeps if the program needs your attention). These input and output devices are discussed in separate sections of this tutorial.  Personal computers are used in a very interactive manner, with the user continuously inputting data and commands (to choose various program functions), and monitoring the output displaying the results of the commanded operations. This is very different from the way older large computers were used (where the user provided input in one operation, and received the output back later, in what is called batch processing).