1.7 Input, Process and Output
When a computer is asked to do a job, it handles the task in a very
- It accepts
the information from the user. This is called input.
- 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.
- 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.
- 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.
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
- An electric
circuit flows through the circuit or
- 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.
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.