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Computer Appreciation

1.7 Input, Process and Output





When a computer is asked to do a job, it handles the task in a very special way.

  1. It accepts the information from the user. This is called input.
  2. It stored the information until it is ready for use. The computer has memory chips, which are designed to hold information until it is needed.
  3. It processes the information. The computer has an electronic brain called the Central Processing Unit, which is responsible for processing all data and instructions given to the computer.
  4. It then returns the processed information to the user. This is called output.

Every computer has special parts to do each of the jobs listed above. Whether it is a multimillion-dollar mainframe or a thousand dollar personal computer, it has the following four components, Input, Memory, Central Processing, and Output.

The central processing unit is made up of many components, but two of them are worth mentioning at this point. The se are the arithmetic and logic unit and the control unit. The control unit controls the electronic flow of information around the computer. The arithmetic and logic unit, ALU, is responsible for mathematical calculations and logical comparisons.

Input Devices









To better understand how a computer handles information and to also understand why information is lost if the power goes off, letís take a closer look at how a computer handles information. Your computer is made of millions of tiny electric circuits. 

For every circuit in a computer chip, there are two possibilities:

  1. An electric circuit flows through the circuit or
  2. An electric circuit does not flow through the circuit.

When an electric current flows through a circuit, the circuit is on. When no electricity flows, the circuit is off. An "on" circuit is represented by the number one (1) and an off circuit is represented by the number zero (0). The two numbers 1 and 0 are called bits. The word bit comes from "binary digit". Each time a computer reads an instruction, it translates that instruction into a series of bits, 1ís and 0ís. On most computers every character from the keyboard is translated into eight bits, a combination of eight 1ís and 0ís. Each group of eight bits is called a byte.

Byte Ė The amount of space in memory or on a disk needed to store one character. 8 bits = 1 Byte

Since computers can handle such large numbers of characters at one time, metric prefixes are combined with the word byte to give some common multiples you will encounter in computer literature.

Kilo means 1000 kilobyte (KB) = 1000 Bytes

Me.g.a means 1,000,000 me.g.abyte (MB) = 1,000,000 Bytes

Giga Means 1,000,000,000 gigabyte (GB) = 1,000,000,000 Bytes

As a side note, the laptop computers that you are using at Floyd Colle.g.e have 32 MB of RAM.

At this point it would be good to point out why information stored in RAM is lost if the power goes off. Consider the way the following characters are translated into binary code for use by the computer.

A 01000001

B 01000010

C 01000011

X 01011000

Z 01011010

1.       00110001

2.       00110010

Consider the column at the right, which represents how the computer stores information. Each of the 1ís in the second column represents a circuit that is "on". If the power goes off, these circuits can NOT be "on" any more because the electricity has been turned off and any data represented by these circuits is lost.

Central Processing Unit (CPU)

The central processing unit is one of the two most important components of your microcomputer. It is the electronic brain of your computer. In addition to processing data, it controls the function of all the other components. Intel makes the most popular microprocessors in IBM compatible computers. The generations of microprocessors are listed below.

         1981 8088

         1984 80286

         1987 80386

         1990 80486

         1993 Pentium

         1996 P-6

Output Devices





         Daisy Wheel

         Dot Matrix


         Ink Jet


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