Computer Basics
What
is A Computer
A computer is an electronic
machine that accepts information, stores it until the information is needed,
processes the information according to the instructions provided by the user,
and finally returns the results to the user. The computer can store and
manipulate large quantities of data at very high speed, but a computer cannot
think. A computer makes decisions based on simple comparisons such as one
number being larger than another. Although the computer can help solve a
tremendous variety of problems, it is simply a machine. It cannot solve
problems on its own.
History of Computers
Since civilizations began,
many of the advances made by science and technology have depended upon the
ability to process large amounts of data and perform complex mathematical
calculations. For thousands of years, mathematicians, scientists and
businessmen have searched for computing machines that could perform calculations
and analyze data quickly and efficiently. One such device was the abacus.
The abacus was an important counting machine in ancient Babylon, China,
and throughout Europe where
it was used until the late middle ages. It was followed by a series of
improvements in mechanical counting machines that led up to the development of
accurate mechanical adding machines in the 1930’s. These machines used a
complicated assortment of gears and levers to perform the calculations but they
were far to slow to be of much use to scientists. Also, a machine capable
of making simple decisions such as which number is larger was needed. A
machine capable of making decisions is called a computer.
The first computer like machine was the Mark I developed by a team from IBM and
Harvard University. It used mechanical telephone relays to store
information and it processed data entered on punch cards. This machine
was not a true computer since it could not make decisions.
In June 1943, work began on the world's first electronic computer. It was
built at the University of Pennsylvania as a secret military project during
World War II and was to be used to calculate the trajectory of artillery
shells. It covered 1500 square feet and weighed 30 tons. The
project was not completed until 1946 but the effort was not wasted. In
one of its first demonstrations, the computer solved a problem in 20 seconds
that took a team of mathematicians three days. This machine was a vast
improvement over the mechanical calculating machines of the past because it
used vacuum tubes instead of relay switches. It contained over 17,000 of
these tubes, which were the same type tubes used in radios at that time.
The invention of the transistor made smaller and less expensive computers
possible. Although computers shrank in size, they were still huge by
today’s standards. Another innovation to computers in the 60’s was
storing data on tape instead of punch cards. This gave computers the
ability to store and retrieve data quickly and reliably.
Classification of Computers
a.
Mainframe Computers
b.
Minicomputers
c.
Microcomputers
d.
Supercomputers
Mainframe computers are very large, often filling
an entire room. They can store enormous of information, can perform many
tasks at the same time, can communicate with many users at the same time, and
are very expensive. . The price of a mainframe computer frequently runs into
the millions of dollars. Mainframe computers usually have many terminals
connected to them. These terminals look like small computers but they are
only devices used to send and receive information from the actual computer
using wires. Terminals can be located in the same room with the
mainframe computer, but they can also be in different rooms, buildings, or
cities. Large businesses, government agencies, and universities usually
use this type of computer.
Minicomputers are much smaller than mainframe
computers and they are also much less expensive. The cost of these
computers can vary from a few thousand dollars to several hundred thousand
dollars. They possess most of the features found on mainframe computers,
but on a more limited scale. They can still have many terminals, but not
as many as the mainframes. They can store a tremendous amount of
information, but again usually not as much as the mainframe. Medium and
small businesses typically use these computers.
Microcomputers are the types of computers we are
using in your classes at Floyd College. These computers are usually
divided into desktop models and laptop models. They are terribly limited
in what they can do when compared to the larger models discussed above because
they can only be used by one person at a time, they are much slower than the
larger computers, and they cannot store nearly as much information, but they
are excellent when used in small businesses, homes, and school classrooms.
These computers are inexpensive and easy to use. They have become an
indispensable part of modern life.
Computer
Tasks
a.
Input
b.
Storage
c.
Processing
d.
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 (CPU) is the electronic
brain of the computer. The CPU in a personal computer is usually a single
chip. It organizes and carries out instructions that come from either the
user or from the software. The processor is made up of many components,
but two of them are worth mentioning at this point. These 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.
The processor is plugged into the computer’s
motherboard. The motherboard is a rigid rectangular card containing the
circuitry that connects the processor and all the other components that make up
your personal computer. In most personal computers, some of the
components are attached directly to the motherboard and some are housed on
their own small circuit boards that plug into the expansion slots built into
the motherboard.
Input
Devices
A computer would be useless without some way
for you to interact with it because the machine must be able to receive your
instructions and deliver the results of these instructions to you. Input
devices accept instructions and data from you the user. Some popular
input devices are listed below.
a.
Keyboard
b.
Mouse
c.
Scanner
d.
Microphone
e.
CD-ROM
f.
Joystick
Memory
A personal computer must have a means of
storing information (data) and instructions so that it can perform processing
tasks on the data. Personal computers have two types of memory.
These are discussed below.
Read Only
Memory (ROM)
ROM is a small area of permanent memory that
provides startup instructions when the computer is turned on. You can not
store any data in ROM. The instructions in ROM are set by the
manufacturer and cannot be changed by the user. The last instruction in
ROM directs the computer to load the operating system.
Every computer needs an operating
system. This is a special computer program that must be loaded into
memory as soon as the computer is turned on. Its purpose is to translate
your instructions in English into Binary so that the computer can understand
your instructions. The operating system also translates the results
generated by your computer into English when it is finished so that we can
understand and use the results. The operating system comes with a
computer.
Random Access Memory
(RAM)
This is the area of memory where data and program
instructions are stored while the computer is in operation. This is
temporary memory.
NOTE: The data stored in RAM is lost forever
when the power is turned off. For this reason it is very
important that you save your work before turning off your computer. This
is why we have peripheral storage devices like your computer’s hard disk and
floppy diskettes.
Permanent Memory (Auxiliary Storage)
·
Your files are stored in permanent memory only when
saved to your disk in a: drive or saved to your computer's hard disk,
·
Drive c: In the Floyd College labs, you can
also save your work to a network drive. We will discuss this in class.
To better understand how a computer handles
information and to also understand why information is lost if the power goes off,
let’s 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, 1’s
and 0’s. On most computers every character from the keyboard is
translated into eight bits, a combination of eight 1’s and 0’s. Each
group of eight bits is called a byte.
Byte – 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) = 1024
Bytes
Mega means 1,000,000
Megabyte (MB) = (1024)2 Bytes
Giga Means 1,000,000,000
Gigabyte (GB) = (1,024)3 Bytes
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 1’s in the second column
represents a circuit that is “on”. If the power goes off, these circuits
can NOT be “on” anymore because the electricity has been turned off and any
data represented by these circuits is lost. This is why we cannot
overemphasize the importance of saving your work often.
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. The most popular microprocessors in IBM compatible computers
are made by Intel. The generations of microprocessors are listed below.
Year Processor
1981
8088
1984
80286
1987
80386
1990
80486
1993
Pentium
1996
P-6
1998
Pentium III
2000
Pentium IV
Your computer has a Pentium IV processor.
Output Devices
i)
Monitor
ii)
Speakers
iii)
Printer
(i)
Impact
i.
Dot Matrix
(ii)
Non-Impact
i.
Ink Jet
ii.
Laser
Storage Devices
a.
Hard disk
b.
Floppy disk
c.
Tape drive
d.
CD-ROM
Telecommunications
Telecommunications means that you are communicating
over long distances usually using phone lines. This enables you to send
data to and receive data from another computer that can be located down the
street, in another town, or in another country. Telecommunications
requires a communication device called a modem, which connects your computer to
a standard phone jack. A modem converts the digital signals that
your computer uses into analog signals that can be transmitted over the phone
lines. To use a modem, you must also have communication software to
handle the transmission process.
Computer Software
System Software
System software will come provided with each
computer and is necessary for the computers operation. This software acts
as an interpreter between the computer and user. It interprets your
instructions into binary code and likewise interprets binary code into language
the user can understand. In the past you may have used MS-DOS or
Microsoft Disk Operating System which was a command line interface. This
form of system software required specific commands to be typed. Windows
95 is a more recent version of system software and is known as a graphical
interface. This means that it uses graphics or "icons" to
represent various operations. You no longer have to memorize commands;
you simply point to an icon and click.
Program Software
Program software is software used to write computer programs in specific
computer languages.
Application Software
Application software is any software used for specified applications
such as:
i.
Word Processing
ii.
Spreadsheet
iii.
Database
iv.
Presentation Graphics
v.
Communication
vi.
Tutorials
vii.
Entertainment, Games
No comments:
Post a Comment