WHAT IS A COMPUTER?
Computer is a machine that makes
work easier, a lay man said. Though he is not far from the definition of it.
Expert’s as a programmable electronics device capable of accepting data in a
prescribed form through input device and processes the row data through the
central processing and produce the reform through the output device.
Computer
has three component parts which are interdependent. That is, without this parts
combining together it is incomplete. They are the keyboard, central processing
unit also known as the system unit and the monitor or display unit.
COMPONENT PART OF THE COMPUTER
1.
keyboard:
This is an input device use for sending/inputting data or information into the
computer. It is very similar to the typing keys of the typewriter. It is
divided into different areas as follows:-
1.1
Typing keys:
It is also known as typewriter keys. This is the alphabetical area (A-Z) used
or alphabetic data(s)
1.2
Numeric keys:
It is used for inputting numbers.
1.3
Functional keys:
These are series of keys (F1-F12) that have their usage depending on a
particular application.
1.4
Cursor keys:
These are keys that aid the movement of the cursor, they include arrow keys (←↑→↓),
Page Up, Page Down, Home, End, Delete, Insert.
1.5
Modify keys:
This includes Ctrl, Alt, Shift, they are also called because they depend on
other keys to carry out their functions.
1.6
Indicator area: Keyboard
also has a status indicator area. This area has three lights that display
status (on or off). They are Num Lock, Scroll Lock, Cap Lock. This three keys
toggle there respective mode on or off when they are pressed.
Num lock: Toggles the key of the
numeric keypad between cursor movement and numeric entry.
Caps lock: toggles the letter keys
between lower case and upper case.
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2.
System unit:
it is also known as central processing unit. It refines row data into tangible
form. Hence it is said to be the heart of the computer. It receives data from
the keyboard and gives out data through the monitor. There are three main
unseen elements involved in the performance of this duty, namely- the main
memory, the arithmetic logic unit.
3.
The main memory:
It is also known as the internal storage devices. This holds program to be
executed and the associated data. Its of two types ROM and RAM.
Rom (read only memory): can only read
from, neither can the contents be tempered with. It holds information
permanently.
Ram (random access memory): This
section holds programmes, instruction and data being processed and stored
intermediate results of processed data awaiting transfer to the output device
or storage device.
3.
Control units: this
device is responsible for controlling and co-ordinating all other devices. The
controlling and coordinating is done by encoding and decoding i.e. interpreting
and implementing. It does the inputting of data, processing the data and
outputting the data.
5. Arithmetic logical unit (ALU): This consist of two units, The
Arithmetic Unit and Logical Unit. The Arithmetic Unit function such as
addition, subtraction, multiplication, and division.
6. The logical unit: Performs logical operations such as or, not, and,
e.t.c.
7. Monitor: it can also be called the visual display unit or the
screen. It is an output device responsible for displaying any information after
being processed. It you with the visuals of your work.
HISTORY OF COMPUTER
Man has tried to manipulate figures
in all kinds of ways since 17th century. The invention of modern day
computer actually took place in 1946, by two Americans, pro Eckett and
marcualey in the University of Pennsylvania. Before these people came up with
this computer there have been cases where people like John V. Atanasoff,
Clifford and Bery attempted to build a computer in 1942, called A.B.C though it
did not receive any attention. In 1944, another group came together to complete
Mark 1 computer incorporation with Howard University U.S.A, another Mark 1 has
760K electric connecting by 500 miles of wires, 300 relays and it is housed in
a whole building.
In
1946, two Americans, pro Eckett and marcualey of University of Pennsylvania
invested the computer called ENLAC (Electronic Numerical Integrator and
Calculator). After studying ABC; it contained 18,000 vacuum tubes, 80,000
resistors and capacitors, and weighs 30 tons. It has an area of 15,000sq fit.
it uses much electricity that dims in Philadelphia region when it is switched
on and it is faster than Mark 1. It runs for 9 years and now on exhibition at
usylvan University.
In
1949, John Von Newman improved on the ENIAC and called it EDVAC (Electronics
District Automatic Computer). It uses the concept at storage programmes, which
meant the computer needs on rewiring like the ENIAC.
In
1950, the inventors of ENIAC improve on the machines and called it UNIVAC
(Universal Automatic Calculator). At the stage of development, the working of
the machines are based on tubes and valves, therefore it has so many
disadvantage, some of which are large storage spaces for the computer, high
cost, generation of intensive heat, and very low speed. Dating from last 1960s,
the use of integrated circuit was supplied to computer and it therefore brought
a substantial reduction in size, cost, and heat. By mid 70s the modern day
computer using high languages involving very large scale integrated circuit and
with component in hundreds of small clips have been invented.
Since
the invention of modern computers, the machine and greatly being improved upon
it terms of size, efficiency, speed of operation and storage capacity.
GENERATIONS OF COMPUTER
Just like human generations,
computers too have been divided into different group of generations.
FIRST GENERATION (1945-59): The computers of this period where
machines, which have tubes and value switching devices. They input data using a
punched card and output was on paper or on a magnetic tape. It marked the
beginning or programming and programming language consisting of zeros and ones
(0s & 1s). They feature as low speed, low memory, high failure rate, high
cost & very large size e.g. ENIAC.
SECOND GENERATION (1960-65): This computer uses transistor instead
of tubes, these transistors were smaller, faster and more reliable and produced
less heat. They use magnetic tape instead of punched card, for storage, input
and output. It marked the beginning of the use of high level languages (FORTRAN)
a specific programming language. Cobolfo business e.g. DECPDP-1 minicomputer.
THIRD GENERATION (1966-75): This marked the introduction of IBM 300
computer. Integrated circuit (IC) was used with transistors. It marked the
beginning of keyboard input and visual display unit of output. The circuit
board became smaller and contained more switches now known as chips. This generation
witnessed rapid growth, increased processing speed, increased accuracy, low
price, less heat and reduced size.
FORTH GENERATION (1975-90): It saw the arrival of microcomputers.
The use of the very large scale integrated circuit (IC) was introduced, so also
were the development and the use of microprocessor. Input and output devices
were improved upon and many languages were developed to solve business
problems. E.g. IBM, Apple, Commodore etc. it witnessed smaller CPU, faster CPU,
and low cost. These marked the computer age.
FIFTH GENERATION (1990-TILL DATE): The PC’s at the generation are
being developed in Japan, USA and Europe; they are expected to process
knowledge rather than data. With the arrival of Pentium and its advancement,
the signs for future PC are rather being felt. They are expected to diagnose,
hypothesis and make inferences, great improvement in computer technology,
improves speed and storage capacities.
TYPES OF COMPUTERS
1)
DIGITAL
COMPUTER: These are computers that understand the string of 0 & 1
digital are commonly in business environment i.e. bank.
2)
ANALOGUE
COMPUTER: These are machines that are used for data collection and they are
base on analogue signal. Use for war, games, to focus weather.
3)
HYBRID COMPUTER:
It has the function of both the
analogue and the digital computer e.g. house manager.
CLASSES OF COMPUTER
There are four
classes of computer which include:-
a)
Micro Computer.
b)
Mini Computer.
c)
Mainframe Computer
d)
Super Computer
a)
MICRO COMPUTER: this
is the forth generations of PC’s, manufactured in the 70s. they are smaller and
cheaper (meaning smaller in size). They are also referred to as PC (personal
computer) or work station. The liked of the PC’s are laptop, palmtop, hand
held/pocket size pc.
b)
MINI COMPUTER: It
is physically larger than the micro computer,it was develop for the use of the
military and was used before the arrival of the micro computers. Today, mini
PC’s are being used in an organization where large amount of data are processed,
they can serve a number ranging up to 40,000 users. It is very expensive most
modern armies have mini computers which are used on the battle field to process
large amount of data’s received from satellite e.g. Hp1000, DG900, PDP11 and
PD8-/E.
c)
MAINFRAME COMPUTERS:
It processes vast amount of datas. IBM is a major supplier. They are very large
and have to be housed in a special room whose temperature and humidity are low.
It is very expensive and is avoidable mostly by multinational companies and
government parastatal. It processes a very large amount data in seconds and
respond to thousand of users simultaneously.
d)
SUPER COMPUTERS:
It processes large gigantic data in the quickest possible time and very
expensive to buy. They are commonly used by spaces center worldwide.
COMPUTERIZATION
Computerization is the act of
working with a computer system. There are three elements that are involved. We
have the hardware, software and peoples ware. These elements compliment each
other.
HARDWARE
This is the physical element of the
computer. They are physical because we can see and touch them. they are divided
into input device, output device, and storage device.
- INPUT DEVICE: this is the means by which data are sent into the computer through the keyboard, mouse, joy stick e.t.c. therefore, before data can be processed it must be read from an output and then store in the main memory of the computer. This data must be properly supplied to give tangible results, Hence in computer language we say garbage in garbage out (GIGO).
SOMETYPES OF INPUT DEVICES
a)
MOUSE: this
is the most recent development it’s the type of input devices that allows the
user to move the cursor on the screen to perform a specific function by moving
the “Hand Hold Device” on a flat surface called the mat mouse, it is attached
to the computer by a cable that transmit’s movement over a flat surface.
The
mouse has a bottom that can be clicked to signal the computer in which the
selection be pointed to. The process of pressing down the mouse is called
“clicking”. This can be done in three ways Right Clicking, Left Clicking,
Double Clicking.
b)
WORKLATE: it
is also known as digitizer pad, it is attached to the computer through a cable.
The work slate is sensitized and when the user draws on it, the image also
appears on the display unit. It is basically used for graphic designing.
c)
SCANNER: It
is a machine use for transferring pictures, images, etc into the computer. When
an image or picture is scanned it appears to the display unit exactly as it is.
d)
JOYSTICK: This
is another input device used for playing games. When connected to the system
unit, it can be used to play all kind of games
e)
LIGHT PEN:
This is inform of a pen and can be used on the screen, whenever you write or
draw on the display screen, it appears inside, it has a cable connected to the
system unit.
f)
KEYBOARD: It
is also an input device. (read detail, in component of system unit)
2.
OUTPUT DEVICE: The
Output of a computer system depends on the users name and application. Computer
users are confronted with all kind of assorted computer output systems which
range from graphic design, text etc.
SOME TYPES OF OUTPUT
DEVICE.
a)
DISPLAY UNITS: It
is also called monitor. It is used for displaying the data inputted. A well
designed screen is adjustable so that it can be lifted and swived for
convenience purposes. Some screens are single coloured(monochrome), and others
in colour forms (VGA adapters), SVGA, etc. it is of various sizes ranging from
12 inches, 14 inches, 17 inches, 21 inches, 24 inches etc. As data’s are entered
from the keyboard each characters are displayed on the screen which allows the
user to make immediate correction.
b)
PRINTER:
This produces hard copy of an information on a paper, unlike the monitor that
produces a soft copy. The printer
differs base on size and use to produce variety’s of work. Some are commonly
known printers are dos matrix, Desk jet, LaserJet, Line printer. Etc.
DOS MATRIX PRINTER: It is a printer
which printing quality is in dot. It is noisy and spends much time in printing
e.g. Epson LQ & FX printers.
LINE PRINTERS: It prints out in line on
the paper e.g. HP Deskjet, HP Officejet.
MIN HEAVY DUTY: it prints out in full
page or job at a time. It prints in 3 seconds e.g. HP Laserjet 4M plus, Canno
Laser 1100, etc.
3.
STORAGE DEVICE: Apart
from the main memory we also have we also have an auxiliary storage device that
act as a backup. That is , it assist the main memory in storing information
that are not presently required. i.e. disks, video cd’s, etc they can store
information for a very long period time.
a)
DISK: They are used for recording with the micro
computers. The amount of information they can hold depends on the sizes,
density or type. i.e. floppy disk, CD, Hard Disk.
i.
FLOPPY DISK:
It is a round magnetically coated plastic disk inside a protective jacket. They
are two sizes 5.25 or 3.5 inches and have different storage capacity’s. the
5.25 inches floppy disk is inside a hard plastic case.
PART OF A DISKETTE
PROTECTIVE CASE: This keeps dirty, dust
and other harmful material from touching the delicate surface of the diskette.
LABEL: This is where you can write on
the disk.
DISKETTE HUB: The round hole in the
middle of the diskette where the disk drive mechanism actually touches the disk
to make it spin.
READWRITE OPENING: This is where the
computer get or put information off or into a diskette.
MEDIA: This is the surface of the
diskette that is shiny and looks kind of reddish or brownish. This is the
actual place where the information reads/writes from/to.
WRITE PROJECT NOTCH: This helps you
prevent accidental damage to a diskette.
WRITE PROJECT TAB: A small piece of
silver in the box that your diskette came with and also serves as the lock.
HANDLING OF A DISKETTE
1.
A diskette should not be folded or bent.
2.
The exposed area should not be touched.
3.
Diskette should be returned to the file jacket after
use.
4.
Diskette should be inserted carefully into the drive.
5.
Do not place the diskette in a hot environment or near
magnetic objects.
ii COMPACT
DISK (CD): A non magnetic optional disk used range amount of information. A
CD can store 600mb of information, equivalent to over 1700 double density
floppy disk.
iii HARD DISK: This referred to the hard disk drive that stores
data/information and not the part that records or reads from it.
COMPUTER BUTTON
POWER BUTTON: This button turns your computer on or off.
TURBO BUTTON: This button toggles between off and on. If ON increase the speed, if OFF reduces it.
RESET BUTTON: This button restarts your system if there is a system
failure.
KEYLOCK BUTTON: This button helps your computer with the system
key. Thereby prevent others from using it.
COMPUTER LIGHT
They are up to 5 light in the CPU.
POWER INDICATORS: Comes on when you switch on the system.
TURBO: Comes on when the turbo button has been put on.
ADD (HARD DISK DRIVE): Comes on when the computer is reading from
hard disk or copying information to a hard disk.
ADD (FLOPPY DISK DRIVE): This is found on the floppy disk drive
comes up when computer is reading or writing information from/to the floppy disk.
DIGITAL SPEED: This displays a digital number which represents
speed at which your computer works.
SOFTWARE
They are set of computer programmes
that operates and perform specific task. This programmes are detailed step by
step instruction that tells a computer how to carry out a specific task. They
are written in programming languages such as basic, Pascal, etc. It is usually
distributed in one or more diskettes. There are two types of software which
are.
- Operating System: This manages most of your computer activities including the allocation of computer resources, maintenance of files and running of application software. As a resource manager, the operating system (OS) controls the flows of information through the computer. E.g. data accepting by the keyboard, seen on the display or sent to the printer is under the control of the operating system. As file manager the operating system is sued to name, save, retrieve, and maintain the program and data file you create on the computer. (a file is a collection of related records e.g. letter).
It is also a vital
link between the computer hardware and the application software. There are
various types of operating system e.g. Ms DOS, Windows, Novel, Unit, Macintosh
etc. (note: Novel and Unit are
basically network programmes).
- Application Software: It is designed to help accomplish a certain type of task like typing letters, calculating, designing, etc. example are Word Processing, Database Management, and Spreadsheet.
PEOPLE WARE
This refers to the interface between
the hardware and the software. Basically, those operating the computer are
known as people ware. They complete the computerizing system. A computer might
be ready with its software, someone need to operate it. The computer world
recognizes these three independent parts before it is fully put to use.
Although much have not been said about the people ware.
WHY DO WE COMPUTERRIZE
The
main reasons why organization and individual decide to use computers are as
follows:-
- Computers are very faster in carrying out it operations.
- Computers has very large capacity, where large numbers of data can be stored in its memory for future reference.
- The overall cost for computerization is very low compared to manual processing cost. i.e. consider a company with 10,000 employee, computer makes it easy to reach them on time.
- It assist in decision making, that is , it delivers information in timely manner. E.g. employing, recruitment, promotion etc.
- It accommodates growth, that is, computer enables some organization to move forward thereby compete with other firms.
- computer improves overall qualities of life, that is, it assist in improving various forms of life. E.g games etc.
VIRUS AND ANTIVIRUS
Virus can be defined as a piece of
rebellious software which puts itself inside another programme and duplicate
itself by spreading from memory to storage and even into diskette. This affect
the well functioning of other programs and the program may become malfunctions
or inaccessible. They produce variety of symptoms in the system. Some even
multiply without much change. They can damage files and hard disk. There are
various types of virus which include file
infector and Trojan horse.
- File Infector: A file infector virus adds code to the file that runs program. When the program is running the virus spread to other program. This virus is very effective and can damage files and program e.g. anti com viruses. This set of virus can oly be removed by using an antivirus programme from a clean disk.
- Trojan Horse: These are the most destructive viruses and are difficult to recognize once they infected file or disk they may not be removed again. One thing about this virus is that they are distinguished as legitimate programs.
HOW TO PREVENT AGAINST VIRUS
Virus can be prevented through the
following ways:-
- Install anti virus software’s on your system that will automatically detect virus when virus infected disk is inserted.
- Turn the system essential files to read only. Files like command.com, config.sys and auto exe.bat and programmes executable files.
- Rightly protect your disk if allowed scan it first before using it.
- When a virus is discovered stop work immediately and cleanse the virus from such disk then boot the system again.
- Make sure the computer environment is always clean and free from dust.
- Don’t eat anything that will attract insect and throw it into the computer system.
- Always be current with latest antivirus and have a copy on your computer.
ANTIVIRUS
No matter how dangerous and
destructive a virus can be, there is antivirus program to clean such virus.
Antivirus are program written to prevent, cleanse and attach virus infected
file or disk. There are many antivirus programme, they include central
processing antivirus (CPAV), Microsoft antivirus (MAV), f piol antivirus,
doctor Solomon antivirus (toolkit), windows 95 antivirus, Norton antivirus
(NNAV), windows 97,98 and 2000 antivirus.
EXAMPLE OF VIRUS
VIRUS NAME TYPE
FILES NFECTED
AID TROJAN COM
DEMON TROJAN COM
LEPROSY TROJAN COM
RECOVERY 382 TROJAN COM
AIRCOP BOOT BOOT SECTOR
BLOODY BOOT BOOT SECTOR
DISK KILLER 2 BOOT BOOT SECTOR
HAND HONG BOOT BOOT SECTOR
AMOEBA FILE COM
CEMENTERY FILE COM
DADA FILE COM
TERRO FILE COM
