INPUT DEVICES

Input devices are necessary to enter data and instructions into a computer. An input device converts input data and instructions into suitable binary form(such as ASCII) which can be accepted by the computer. The commonly used input device is a keyboard. A number of input devices such as mouse, light pen, graphic tablet, joy stick, track nall, touch screen etc have also been developed which do not require typing for inputting information. In recent days voice input systems have also been developed and microphone is used for that purpose.

Features of a computer

1. 
   
   speed, size and cost

The speed of a computer is linked to the technology used to build it. ENIAC was built suing vacuum tubes. With this technology, speed was measured in milliseconds. It could add two numbers in 0.2 milliseconds and multiply them in 3 milliseconds. In other words, it could perform 5000 additions or 300 multiplications per second. It occupied an area of about 150 square meters and cost millions of dollars. It was not very reliable, developing faults (because of blown vacuum tubes)several times per hour.

After the invention of the transistor in 1947, computers were built using transistors replacing vacuum tubes. This decreased the size of the cokputer and increased its operation speed. Speeds were then measured in microseconds. They could perform million additions per second. The price was reduced beceuse of improvement in the technology. In around 1958-1959 integrated circuit (IC) was developed. In a single IC chip, a number of electronic components such as transistors and diodes can be fabricated(made). The typical size of an IC chip is roughly 0.25 square cm (0.5 cm x0.5 cm). So, after the invention of the IC technology, transistors were replaced by ICs in building a computer. The computers developed with ICs were smaller. The use of IC in a cokputer inceased the speed to tens of millions of operations per second.

History of computer

Main article: History of computing hardware

The Jacquard loom, on display at the Museum of Science and Industry in Manchester, England, was one of the first programmable devices.
The first use of the word "computer" was recorded in 1613, referring to a person who carried out calculations, or computations, and the word continued to be used in that sense until the middle of the 20th century. From the end of the 19th century onwards though, the word began to take on its more familiar meaning, describing a machine that carries out computations.
The history of the modern computer begins with two separate technologies—automated calculation and programmability—but no single device can be identified as the earliest computer, partly because of the inconsistent application of that term. Examples of early mechanical calculating devices include the abacus, the slide rule and arguably the astrolabe and the Antikythera mechanism (which dates from about 150–100 BC). Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when.[4] This is the essence of programmability.
The "castle clock", an astronomical clock invented by Al-Jazari in 1206, is considered to be the earliest programmable analog computer.It displayed the zodiac, the solar and lunar orbits, a crescent moon-shaped pointer travelling across a gateway causing automatic doors to open every hour, and five robotic musicians who played music when struck by levers operated by a camshaft attached to a water wheel. The length of day and night could be re-programmed to compensate for the changing lengths of day and night throughout the year.
The Renaissance saw a re-invigoration of European mathematics and engineering. Wilhelm Schickard's 1623 device was the first of a number of mechanical calculators constructed by European engineers, but none fit the modern definition of a computer, because they could not be programmed.
In 1801, Joseph Marie Jacquard made an improvement to the textile loom by introducing a series of punched paper cards as a template which allowed his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.
It was the fusion of automatic calculation with programmability that produced the first recognizable computers. In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer, his analytical engine.Limited finances and Babbage's inability to resist tinkering with the design meant that the device was never completed.
In the late 1880s, Herman Hollerith invented the recording of data on a machine readable medium. Prior uses of machine readable media, above, had been for control, not data. "After some initial trials with paper tape, he settled on punched cards ..."To process these punched cards he invented the tabulator, and the keypunch machines. These three inventions were the foundation of the modern information processing industry. Large-scale automated data processing of punched cards was performed for the 1890 United States Census by Hollerith's company, which later became the core of IBM. By the end of the 19th century a number of technologies that would later prove useful in the realization of practical computers had begun to appear: the punched card, Boolean algebra, the vacuum tube (thermionic valve) and the teleprinter.

History of computer in Nepal

There is not a long history of computers in Nepal. Nepal hired some types of calculators and computers for its census calculation. Now-a-days, most of the organizations are using computers for their record keeping,database and communication. Following list shows its history in Nepal.

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  In 2018 BS,an electronic calculator called Facit was used for cinsus.


• In 2028 BS census, IBM 1401, a second generation mainframe computer was used.


• In 2031 BS, a centre for Electronic Data Processing, later renamed to National Computer Centre(NCC), was established for national data processing and cimputer training.


• In 2038 BS, ICL 2950/10, a second generation mainframe computer was used for the census.


• Now-a-days, probably each and every institutions like schools, colleges, business organizations, communication centres, ticket counters etc. are using computers.

Computer Applications

Computer Applications

1. Banking

Banks use computers for general purpose computations, to maintain ledger, to handle transactions, to make entry in passbooks, to issue fixed deposit receipts, to provide online service to customers who want to perform bank regarding their balance etc. For all these purpose, there is a central computer (a server) which processes all the data from different terminal computers. These days banks also provide the ATM service to the customers. A customer with the ATM card can perform a cash transaction immediately with the ATM machine by inserting card in it.

2. 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:

(a) Employee records

All organizations keep records of their employees. An employee record normally contains information such as name, address, telephone number, ptersent job classification, date of the appointment, contract period, salary scale or rate of pay, allowances, deductions, salary paid to date, taxes deducted to date etc. Using a computer, it is a simple matter to store,retrieve and update information concerning employees. The most frequent use of an employee record is in payroll processing.

Computer Introduction

Computer technology has brought enormous changes in the world. No society and individual member can stand apart and survive in isolation from the global influence of computers. Our day-to-day interactions have taken universal shape at the root of which, computer has played vital role as changing agent.

Computer is derived from the latin word computere which means calculate. So according to this definition, computer is a machine which can perform calculations at very high speed. In other way, computer can be defined as a digital and automatic machine which takes input from the user,processes it, stores it if necessary and gives output in desired form. From the above definition, we can get some of the characteristics of computer.

computers

Computer have became a part our life. They have been used widely in every field. It is one of the most useful inventions of science and technology. Computers are used in private and government offices, airlines, banks, hotels, schools, colleges,business organizations, industries, factories, agriculture, medicine, communication etc. It is also used for personal works. They are used to keep the record for a long time. They are the source of information. They are the source of knowledge. We can learn many more things by using them. Computer has been introduced as a new method of calculation or ti di mathematical operation. Now, computer has been very powerful device to help on the field of data processing and research. Althought looks small, it does a lot of works.

Computer is also the source of entertainment. We can play diffirent types of games on computer.When we feel bored, we can watch film too. It is also the fastest means of communication. We can sind our message through E-mail. We can talk to other people with the help of internet. Computer have become the must essentosl even in the developing countisd like Nepal. Now we cannot imagine the world without computer.

There are also some disadvantages of computer. After the invention of computer, people have fully depended on it. It has made them lazy and inactive. They use cokputer een fot small works. It has cteated the problem of unemployment. As computer can work fast and efficiently, many people have last their work. It is said that a computer can do the work of twenty people. We know that unemployment creates social problems.