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History of Computer

Computers are developed as a result of man’s search for a faster way to calculate. Computers are very fast because data and instructions are represented as pulses within electronic circuits and they travel at the speed of light. Around the fifth century AD Hindu philosophers developed a new method of counting from 0 to 9. This system of counting is called the decimal method. The numbers stated above (0 to 9) are the digits. Digits are a finger or toe, and counting on one’s fingers is called the digital operations. The vast majority of computers seen today are electronic digital computers and their names suggest that they carry out their work by performing high speed digital operations on data. The first electronic digital computers were built in the mid 1940s. Their forerunners were a number of digital devices, of which the abacus is one.

Kind of Computer

On the basis of work performance, computer can be classified into 3 classes. They are: -
1 Analog computer
An analog computer is the one that measure physical values such as temperature or pressure that fall along a continuous scale or variance temperature or pressure. They are generally use for process control in industries. T his computer is poor then digital computer. Analog computers are even less then 1% in use in Nepal.

2 Digital Computers
These computers are based on binary digits. Binary system is such system of numbering in which only 2 digits are used 0&1. Meaning of 0 is off and 1 is on. Digital computers are mostly used in the preparation of reports, result, tabulation, & graphic representation. Example of those computers is IBM Pc, Apple Macintosh etc.

3 Hybrid Computers

Hybrid computers comprise both the facilities of analog and digital computer. Hybrid computer can convert analog signals into digital and digital to analog signals these computers are mostly used in spacecraft, bombers, fighters space war, scientific applications and industrial control processes etc.

On the basis of size, computer can be classified into 3 classes. They are
Mainframe computer
These are the largest computers on the basis of large size. A centrally located server or CPU is connected with more than 100 terminals5. Examples of these computers are IBM 1401, ICL 2950/10 etc.

Mini Computer:
Mini computers are medium in size, which means, it is a bigger than microcomputer and smaller than mainframe computer. It is communicate with 50 terminals. At a time at least 50 persons can work with single mini computer for data processing. Examples of these computers are VAX 7500, Digital PDP 11 etc.

Micro Computer:
These are the smallest computer system on the basis of size. These computers are called micro because microprocessor is used as memory device and they are very small. The computers are also called PC (Personal Computer) or home computer. The smallest of this category are laptop, notebook and palmtop computer. The size is reducing day-by-day. Examples of these computers are IBM Pentium PC, Apple/Macintosh etc.

On the basis of brand, computers can be classified into following categories
1. IBM PC (International Business Machines):
IBM Corporation was established in 1924 AD in the USA. IBM is one of the largest computer companies in the world. IBM is one of the leading companies in computer manufacturing. These are reliable, durable, accuracy, strong and they high speed processing.
2. IBM Compatible:
Compatible means principle or ideas that can exist together and the computers manufactured based on IBM principles are called IBM compatible computer. IBM compatible computers are nearly 80% in the world. Some IBM compatible computers used in Nepal are AST, SCAN, ARL (Advance Logic Research), NEC (Nippon Electronic Company), Spectrum, Agtec, Sherry, IT 2000, Litron System, Compaq, Syntax, Wang, Laser etc.

3 Apple/Macintosh Computers
This computer is established from Apple Company by Steve Jobs and Steve Wozniak in 1976AD. All the computers that are developed by Apple Corporation are called Apple/Macintosh computers. These computers are architecturally totally different that that of IBM’s. Not only hardware part, but their software architecture is also totally different. Software made for IBM PC can’t run in Macintosh or vice versa. These computer are mainly used for word processing and generally used for printing like magazines, newspaper etc.

Computer System

There are many devices (Part) of the computer system. Among these part, there are main & necessary to run the computer.
Central Processing Unit (CPU)
The brain of any computer system is the processor unit or Central Processing Unit. All the cables of computer’s devices are connected with CPU. All the processing arithmetical and logical operations and storage are done in this unit. CPU is made up the main three units they are:
I. ALU (Arithmetic and Logical Unit)
II. CU (Control Unit)
III. MU (Memory Unit)

Monitor: -
Every computer must have a display terminal called Visual Display Terminal (VDT) or Visual Display Unit (VDU). Monitor is an output device of computer system. It is looks like a TV screen. The monitor has usually 24 lines or rows and 80 columns. They are two types:

• Monochrome Monitor
• Color Monitor.

Keyboard
Keyboard is an input device for every computer in micro, mini & mainframe computer, keyboard are the main input device. It is made of rectangle plastic plate with any buttons there are three types of keyboard.
(I) XT keyboard (83 keys)
(II) At keyboard (100 keys)
(III) Enhanced keyboard (100 or more keys)
The keyboard contains the following types of keys
(a) function key
(b) alphabet and number keys
(c) special or main keys
(d) arrow keys
(e) numeric key

Disadvantage of Computer

1. It is expensive and is beyond the reach of poor people. This limitation is being overcome because its cost is drastically decreasing day by day.
2. Since, it is much reliable, sometimes the failure in devices and program can produce unreliable information and cause loss of data in a great extent.
3. It is electronic machine, so there is much danger of electronic stock and other physical damages.
4. It increases dependency on machine.
5. Although it helps in faster and cheaper communication, there is much danger of security leakage by third party by which authentication becomes questionable.
6. In underdeveloped countries like Nepal, it increases piracy of intellectual properties in big volume.

Advantages of Computer

1. Computers are 100% accurate and much reliable than any other devices and human being.
2. To store large amount of information in small media.
3. Computer is much faster than man.
4. It is very much useful for repeated jobs, which is hard for man to do.
5. With the help of computer, impossible things are easy to show and simulate.
6. Computer words continuously for a lone time.
7. It is vase atilt of can perform many types of works once at a time.
8. It can be used in multiple fields and becoming more general purposed, as has been mentioned above.

Electronic Fields of Computer

Banking
Banks use computer for general purpose computation, to maintain ledger, to handle transactions, to make entry in passbooks, to issue fixed to deposit receipts, to provide online service to customers who want to perform bank transactions from home terminals and to answer customers at bank terminals regarding their balance etc.
Commercial Enterprises
Many business companies, either large or small use computers to help in the control of daily activities. Some of the more common uses are: -
Employee Records
Payroll Processing
Account Receivable
Account Payable
Stock Control
General Ledger
Industries
Computers are extensively used in industries for automatic control of machine process, measurement and display of electrical and physical quantities.
Retailers
Retailers use a barcode reader to find out the actual cost of the items in the department store. The cost generated by the bar code reader is then added with the help of computer to sum up the total cost. The computer then generates the total bill along with the cost of each item.
Reservation System
Railway offices use computerized ticket reservation system at many important stations. If there had not been the computerized system without linking different stations, then there would be a problem of issuing same ticket to more than one passenger.
Offices: -
Computers are the important resources used in offices. Computer are used in preparing reports, memorandum, copy of advertisement, letter, publicity, contracts, forms, notices, etc., which are the basic works of an office.
Education: -
Computers are use as teaching aid, information resource computing and research tool. When computer is used as teaching aid, it is referred to as computer assisted instruction (CAI). Software fro CAI, can be prepared by class teacher or software package can be purchased. CAI programs can be prepared in a variety of modes, such as tutorial, Discovery, problem solving, modeling, & practice modes.
Health and medical field:-
Computers are widely used in hospitals to help doctoral in diagnosis, information on patients, diseases, treatment, drugs etc .they are also used in administration and in keeping patients records three a re a lot of computerized automatic medical equipments which help in diagnosis of diseases such as CT scan machining, eye testing marching, Ultra zoography equipment etc.

Home:-
Today most of people own a home computer. The name computer can be used in recreational activities, like playing game, listening to music or watching movie, today, people use home computers it access tae internet.
Library:-
A typical library contains thousands of books, magazines, reports and other documents which surds may wise to borrow, answer queries about the status of book more easily than if a manual system was being used.

Recording and Film studios:-
In recording and film studios computers are used intensively. In the early days, recording of music has to be donning at the same time with all the musicians playing in music of the same time. The movie editing was a difficult task. Nowadays these things are becoming easies. The music can be recorded in different tracks. The music editing software is used to edit the different tracks & make a single music. The movie editing is done after the shooting process is completed. Movie editing is done with the special and advanced movie editing software which can handle every frames of the movie. The sound tracks of the movie are recorded after in the editing. Computer help in adding the sound tracks in the exact place of the movie. After the completion of the editing process, the whole final movie film is prepared.

Weather Forecasting:
Weather forecasting is done after the analysis of the image sent by the satellites. The analysis of the images is not possible without the use of the computer .computer analysis the direction of the wind, cloud structures, past data when this type of condition occurred etc, to forecast to weather.
Communication
Computers are massively used in communication. Voice, text, animation, hypertext etc. are transmitted from one place to another by the use of computer modem of telephone line. Communication has been made cheaper by the use of computer.
Research of Universities
Scientific of engineering design of research work involve complex and massive computations. In many cases, simulation is also required. Such complex computations are not possible by hand calculations. So computers are most for this type of work.