CONTENTS
- INTRODUCTION TO COMPUTER
- WHAT IS COMPUTER?
- FEATURES OF COMPUTER
- GENERATIONS OF COMPUTER (1ST TO 5TH Generations)
- TYPES OFCOMPUTER
- CONSTITUENT PARTS OF COMPUTERS
- COMPUTER HARDWARES (Example of computer hardware input & output devices)
- STORAGE DEVICES. Secondary Auxiliary storage devices (Types of secondary storage devices; Diskettes, Cd-Rom Etc)
- COMPUTER SOFTWARES (Types of computers software)
- COMPUTER VIRUS (Types of computer virus)
- COMPUTER ANTI-VIRUS (Types of computer Anti-virus)
INTRODUCTION:
The device computer is of high importance in the society today.
It has been a means of help to mankind for the performance of many tasks.
It is the most fundamental dividends of technology to the human race.
IMPORTANCE:
1. It is used for solving mathematical difficult problems
2. It can be used for banking
3. It is used for internet browsing
4. It is used for the keeping of records in organizations and forms
5. It is used for quick transfer of money through E-banking
6. It is used for quick accessing and sending of maids
7. It is used for the flying of bombs and missals during war
8. It is used for launching of satellite into space.
9. It is used for high security profile
10. It is used for scientific research
11. It is used for general typesetting
12. It is used for making high profile designs.
13. It is used for detecting of diseases in the laboratories
14. It is used for detecting faults and soundness in Aircrafts and other complicated engines
15. It is used in tracing of international boundaries maps etc. PROGRAMS
WHAT IS COMPUTER?
This can be defined as any machine or device that is capable of accepting data
Processing the data and can store or supply the results immediately with the help of stored programs.
NOTE: PROGRAMS are set of instructions which tells the computer what to do. It is referred to as SOFTWARE.
DATA: this is a raw material given to the computer to process.
Examples of data may be seen as in where one is asked a question such as 2x4 OR 1+13 OR11-9 as the case may be. These are referred to as data because those questions are still raw and has not been processed or solved.
(Problem) (Processing) (Result)
1+13 = 14
{Computer)
INPUT OUTPUT
FEATURES OF COPUTER
- Speed: this is the ability to process a data at a very fast rate and accurately.
- Capability: this is the ability to store and process large amounts of data than all other machines
- Versatility: this refers to the computers ability to carry out, calculations, record keeping, graphics designing etc.
- Programmability: this is the ability to obey instructions.
GENERATIONS OF COMPUTER
This refers to the different inventions of computer since 1955 to data.
A new invention led to each new generation.
N/B these inventions and developments and datas of each generations are stated overleaf.
FIRST GEN:(1955 &below) Vaccum tubes/valve
SECOND GEN:(1955 to 1964) Transistors
THIRD GEN:(1964 to 1972) Integrated circuit (I.C)
FOUTH GEN:(1972 to1989) Large scale integrated
FIFT GEN:(1990 to date) Pentium processor
FIRST GENERATION COMPUTER
This is the first attempt made in building computer.
The computer were used to calculate and solve more complex scientific problems.
Some were designed to help in flying bombs and missiles.
These computers makes use of VALVES OR VACCUM TUBE.
The laves are very many, hereby contribute to the largeness of the first generation computer.
SECOND GENERATION COMPUTER
The invention of transistors was dated as for back as1948 by a scientist called WILLIAM SHOCKLEY.
The importance of these TRANSISTORS to the computer systein was made clear in the second computer generation, meanwhile, because the areas of concentration was cantered on reducing the size of the first generation computer which was extremely big, this led to the replacement of VALVE with the TRANSISTORS
THIRD GENERATION COMPUTER
These generations of computer were again more reliable that earlier ones.
Individual transistors were not used any more.
They were replaced by very small materials called SILICON. These are called INTEGRATED CIRCUIT (I.C)
The third generation computer use less power, cost less, smaller in size and are much more, reliable.
FOURTH GENERATION COMPUTER
The fourth computer generation and the third looks so much alike as touching there appear acnes and computers.
This is the period when the SOFTWARE industries emerged which led to the development of mini- COMPUTERS.
As years go by, Mary more circuits could be packed onto smaller pieces of silicon, that a piece of silicon, one centimeter square’ can hold many thousands of transistors.
This piece of silicon and its circuits is often called a silicon chip.
This computer generation used very large-scale integrated circuit (VLSIC)
This is just a upgraded version of I.C (integrated circuits of the 3rd generation) Although.
This silicon chip is very small, it is very powerful.
FIFTH GENERATION COMPUTER
Since reducing the size if the computer and enhancing its power are the areas of concentration;
Movements were made in such way that greater memory capacity was possible.
Large-sized software interims of memory utilization and complexity are introduced.
Additional storage divices and drives as in CD-Rom (computer disk read only memory) were also introduced.
These computers are called MICRO COMPUTERS.
Chips used in microcomputers are called MICROPROCESSORS.
TYPES OF COMPUTER
Computers are classified into two types
v Classification based on the way they operate
v Classification based on the factors in use.
Classification based on the way they operate
1. DIGITAL COMPUTERS: the word “digital”, as used here means whole numbers (discrete). E.g. the channel selector on the television set is a digital device because it restricts you to a distrete set of channels. Digital computers are the most common computers they operate by being given a series of steps of instructions. Examples of digital computers are 1bm 360/370; PDF 11/34, and apple microcomputers often seen in offices and schools.
2. ANALOGUE COMPUTERS: in contrast to digital devices, analogue devices have continuous valves.E.g the volume control on your television set is an analogue devices because it avows you to adjust the volleme continuously is one smooth continuous action, thermometers, speedometers, and the petrol dispensers at the petrol sations. Analogue computer operation by accepting data as a quantity varying over length of time they are mostly found in industries.
3. HYBRID COMPUTERS: these are some properties of both digital and analogue combined together. For example, setting (programming) on a modern day television set involves both digital and analogue. You first select the channel (digital), you then tune the channel until it receives the station you want clearly (analogue), you then store the station on that channel (digital) Hybrid computers are not too common: they operate in a programmed form and combine the properties of analogue and digital. E.g. ROBOT use in an industrial environments Road traffic lights control etc
CLASSIFICATION BASED ON THE FACTORS IN USE:
Such factors are: size of its internal memory, processing capability, price range and speed of operation.
CLASSIFICATION:
1. SUPER COMPUTERS
2. MAINFRAMES
3. MINI COMPUTERS AND
4. MICRO COMPUTERS
SUPER COMPUTER:
These are the largest, fastest and most expensive computers. The cost is serval millions of dollars and the speed is between 600 million to 900 million instructions per second. (MIPS) it is manually used in complex calculations by the scientist for weather fore casting and oil exploration. Etc. CRAY X-MP and CRAY2, which cost about 5 million each.
MAINFRAMES:
A mainframe computer is a large computer in terms of price, size of internal memory and speed. Ranging from $200,000 to several millions of dollars in price. The size of the memory is usually more than 256 megabytes of storage. They are mostly used by large establish mats like umuersities, banks, commercial houses etc.E.g NCR V8800 SYSTEM, IBM 360/370 SYSTEM.
MINICOMPUTER
Minicomputers were developed in the 19705 for specialized tasks (i.e. they are special purpose computer.) they are smaller and less powerful and less expiate, in stall and they require less floor space.
The internal storage capacity of a minicomputer is usually between 128 megabytes and 256 megabytes e.g. VAX 750/600,Ncr9300, DEC, IBM systems 38 and MV 400(DATA GENERAL)
MICRO COMPUTERS:
A microcomputer is a computer whose central processing unit (C.P.U) is based on a microprocessor. Microcomputers are at present the most popular of computers. They are very small and easy to use. They can be linked with mainframes and minis. Most of it today generally have between 16 and128 megabytes. E.g. IBM PC and its compatible, Apple macintosh, etc. they are often called PCS (personal computers) microcomputers has keyboard and also has screen of a television set.
TYPES OF MICRO COMPUTERS
1. DESKTOP COMPUTER
2. LAPTOP COMPUTER
3. PALIMTOP COMPUTER
CONSTITUENTS PARTS OF A COMPUTER SYSTEM
These are the basic elements that make the computer function. These includes:
v HARDWARE
v SOFTWARE
v PEOPLEWARE OR HUMAN WARE
HARDWARE
Hardware is the word used to describe the electro-mechanical components of a computer system. This is the computer equipment itself.
SOFTWARE
Software is the word used for all computer programmes. Programmes are a set of instructions given to computer to perform a particular function. They control how the computer works.
PEOPLEWAY
These are the people working with the computer. Without people, the computer cannot function.
COMPUTER HARDWARE
These are those parts of the computer that we can feel and touch.
EXAMPLES ARE:
1. INPUT DEVICES.
2. ARITHEMETIC AND LOGIC UNIT.
3. CONTROL UNIT.
4. MEMORY.
5. OUTPUT DEVICES.
6. EXTERNAL STORAGE DEVICES.
INPUT DEVICES:
Input devices are equipment used to get instructions into the computer. They accept input data and programmes for processing as does by the human eyes and ears. Some common input devices are:
1. KEYBOARD
2. MOUSE
3. VOICE INPUT
KEY BOARD
The computer electronic keyboard is the most fundamental of the input unit and can be classified into:
v Standard keyboard
v Enhanced keyboard
v Window keyboard/ online keyboard.
DIFFERENCES IN COMPUTER KEYBOARD
The computer electronic keyboards are differentiated based on their function keys. The enhanced keyboard has their function keys arranged from function one to function ten (F1 To F10).
While the STANDARD KEYBOARD’S function keys are arranged from function one to function twelve (F1 To F12).
CATEGORIES OF KEYBOARD BUTTONS
The keyboard buttons are categorized into six parts:
1. The function keys
2. The Alpha- numeric keys
3. The Special character keys
4. The arrow/cursor control keys
5. The Home keys
6. The Editing keys
THE MOUSE
This is another input unit of the computer system, which can be used to send instructions into the computer.
It is oval in shape; it helps to move the pointer around the computer screen. It normally works in conjunction with a keyboard and is dependent on the software being used.
FEATURES OF THE MOUSE
1. It is oval in shape
2. Has a long cable which is assumed as the tail
3. 
Has two buttons (primary & secondary buttons)
Left button Right button
SCANNER
Scanner is an input device. It can be used to record and transfer images and graphics,eren documents into the computer system.
FEATURES OF SCANNER
1. It has cornering
2. It has glass under its covering
3. It has two buttons
4. It has two cables
5. USB cable (Universal serial two cable)
6. Power cord
OUTPUT DEVICES
These are equipments that aids the computer operator to hear or view the output of the computer system.
EXAMPLES:
v PRINTER
v CRT MONITOR (CATHOD RAY TUBE)
v VOICE OUTPUT
PRINTER
This is one of the output devices that helps us to have the hardcopy of our work in a paper.
It produces permanent record in print printers has various types and are dependent on the quality of its production.
EXAMPLES:
Dot Matrix Printers, Hp Laser Jet and DeskJet Printers and Inkjet etc.
FEATURES OF PRINTER
1. It has paper tray for feeding of papers
2. It has two cables (USB$Power cord)
3. It has two or more buttons depending on the model
MONITOR
The most common form of display monitor is the CRT (cathode Ray Tube) Monitor is the type used with microcomputers. The monitor can output either text or pictures or both in monochromes is two colures e.g. black and white.
VIOCE OUTPUT
There are fear specialist applications using computer speech output. One application is a book-recording machine for the blind. Speaker and headphones are examples of audio output.
C.P.U (central processing unit)
This is the center of co-ordination.
The main functional parts of the C.P.U. are:
1. Control unit
2. Arithmetic$ logia unit
3. Main memory
Prograues are run on the C.P.U under control of these mentioned there sections of the C.P.U.
CONTROL UNIT
The control unit is the supervisor of the CPU. It fetches numbers from the memory and interprets them as instructions. IT performs the processing under the control of the stored programs.
ARITHMETIC & LOGIC UNIT
This part does the actual calculations on the data and stores the data in the memory of the computer.
MAIN MEMORY
This is the computer memory, also called the internal memory or primary memory. It is used to store intermediate result and data while the computer is processing. It’s always linked or connected to the instructions and information which are being used by the computer.
This is two parts:
1. Read only memory (RAM)
2. Random Access Memory (RAM)
ROM
This is the preset instruction that tell your computer what to do.
E.g. They tell the computer what to do when the power is turned on, they check to see that the necessary cables are connected.
RAM
This is the part of the main memory that stores your programmes. But your programmes go off immediately the power is off. This is also called the secondary memory.
SECONDARY AUXILIARY STORAGE
This is an additional memory.
It is used to hold large amount of in formation outside the main memory. It is separate from the processor and contained in another box.
TYPES OF SECONDARY STORAGE
The most common types of secondary storage are MAGNETIC Disks (disk pack) and MAGNETIC TAPES.
These are like gramophone records and cassette tapes. In computer, magnetic tapes and magnetic disks are used to hold numeric and character information. When they are played, the computer can read the information held on them. Secondary storage is usually either HARD Disk or DISKETTE.
HARD DISK
Hard disk is one of the magnetic disks housed inside the computers cabinet. Hard disk are similar to diskettes except that they are rigid.
They also have larger storage capacities and can and be the written and read more quickly by the computer. N/B the drive into which the disk fits is called a Disk Drive the storage capacity of hard disk in microcomputer ranges from 1 gigabyte to hundreds of gigabytes.
DISKETTES
Another magnetic disk used by a microcomputer is called diskette. A diskette is a plastic disk in the shape of a circle. Information’s are stored on the two surfaces of the disk. To protect the diskette, it is sealed inside a jacket, which is in the shape of a square. Disk can’t be taken out of its jacket. When you want to play the diskette you place the jacket, which contains the disk in a box shaped device called a disk Dive. The disk drive is connected to the processor of the microcomputer.
COMPUTER DISK READ ONLY MEMORY (CD-ROM)
CD-ROM is a relatively another secondary storage medium. It can hold more than 800 million bytes of data. Information once stored on this device cannot be wiped out. To access the in formation impressed on a CD_ROM, you will require a CD-ROM DRIVE, which is also connected of the computer.
COMPUTER SOFTWARE
Software’s refers to all programs that can be used on a particular system. It applied to all those programs, which in some way can assist all users of a particular type of computer to make the best use of their machine.
Software is generally categorized into two:
1. SYSTEM SOFTWARE AND
2. APPLICATION SOFTWARE.
SYSTEM SOFTWARE
System software are those programs that controls the computer systems. Much of this software are programs that contribute to the control and performance of the computer system. This is also called utility programs.
System software can be further sub-divided into three:
A. Operating system
B. Translators
C. Utilities
OPERATING SYSTEMS
They are the major software required by all computer without them, the computer can not understand your in structions.
E.g. MS Dos: which is used with a single microcomputer.
NOVELL: Used in a network environment where many computers are linked together.
UNIX: Used in a multi- user environment where many people can use one big computer at the same time.
WINDOWS OPERATING SYSTEM: Used with a single microcomputer or in a network environment.
TRANSLATORS
These are used to write other computer software’s or programs.
They help to translate the machine (computer) language to human language.
E.g. FORTRAN, BASIC, LOGO COBOL etc.
UTILITES
They are used for general house- keeping on the computer, such as backing up, copying, sorting and printing your data.
E.g. pc tool, windows explorer, Dos shell, and Norton’s utilities.
APPLICATION SOFTWARE
Application software is those computer programs that gives the computer instructions for the steps to take in a specific task.
Applications software are used with systems software to perform specific tasks given to the computer by the user
E.g. Microsoft word, Ms. Excel, Ms Access, cord Draw, Power Point etc.
COMPUTER VIRUS
Computer virus is a program written by the programmers deliberately to destroy data and files.
More also, it is used to fight against piracy or duplications.
N/B: Virus itself is a disease that penetrates into the systems cabinet and change the mode of behavior of the computer system.
TYPES OF VIRUS
There are two types of virus but these are in sectors:
1. Boot sectors virus
2. File sectors virus
BOOT SECTOR VIRUS
This is a type of computer virus that penetrates into the booting area of the computer system.
FILE SECTOR VIRUS
This is a type of computer virus that attaches the files and folders that are inside the computer system.
COMPUTER NAMES OF VIRUSES
They are:
1. FRIDAY VIRUS
2. LENGTH VIRUS
3. AIDS VIRUS
4. MARIJUANA VIRUS
5. BRAIN VIRUS
6. HAPPYADY JOSU VIRUS
7. NOVEMBER VIRUS
8. DATA CRIME VIRUS
9. RAIN DROP VIRUS
10. SCORES VIRUS
11. COOKIES VIRUS
12. V-SIGN VIRUS.
SYMPTOMS OF VIRUS
This refers to the signs that occur to let us know that the system is contaminated with virus disease.
1. This system refuses to boot when switched on.
2. On the sere an of the monitor, it will display a warning that.
This program has performed illegal operation and should be shutdown”
PREVENTIVE MEASURES
1. Make sure that the computer has Anti-Virus
2. Protect all diskettes in a conducive environment
3. Always update your anti-virus software
ANTI-VIRUS
This in contrast to the virus programs written deliberately to destroy data and files is written to fight against virus.
1. Doctor Solomon anti-virus
2. P.C cillin anti-virus
3. Cater point anti-virus
4. Microsoft anti- virus
5. Norton anti- virus .
