Type Of Computer
Classification of computers
Computer are classified according to the following criteria:
Principle of operation
Computing power memory capacity and cost
Technological development
Principle of operation
- Analog computer
- Digital computer
- Hybrid computer
Anlog Computer
It is a computer that measure continuously changing physical quantities such as current temperature pressure etc. and converts them into quantities which can be used as data for computation. As these computers deal with continuously varying quantities they will give only approximate results. Its output is usually displayed in a meter or scale. Analog computer has low memory and scale. Anlog computer has low memory and fewer functions. These are used for engineering and scientific applications.
- Thermometer
- Speedometer
- Anlog clock
Digital Computer
A digital computer works with digital data. Digital computer uses binary number system. Binary number system consists of only two digits ‘0’ and ‘1’. A digital computer represents data in digital signals. A ‘0’ represents OFF and a ‘1’ represents ON. Digital computer performs arithmetic and logical operations on data. It gives output in digital form.
Digital computer are very fast. These computer can store results. They have large memory(that is data storing capacity) today most of the computers used in offices and homes are digital computers.
The digital computers are further divided into the following two groups.
- Special purpose computer
- General purpose computers
Special purpose computers
Is is a computer designed to solve specific type of problem. The computers used in ships and aircrafts etc.
General purpose computers
It is a computer designed to solve a wide variety of problems ,A general purpose computer can store different programs and process them.
The differences between anolog and digital computers are listed in table 2
Hybrid Computer
A hybrid computer is a combination of both anolog and digital computer . hybrid computer can handle both anlog and digital data. A hybrid computer combines the best characteristics of both the analog and digital computer. It can accept data in both analog and digital form.
Applications
Hybrid computer devices are used in hospitals that may calculate patient’s heart function, temperature and blood pressure etc. this calculation may be converted into numbers and shown in digital form. For example, the vital signs monitoring unit also called (VSM) in short. It has blood pressure monitor ECG monitor, respiratory monitor, and is also used for used for monitoring anesthesia.
- Hybrid computers are also used in spaceships and missile system.
- Hybrid computer machines are generally used in scientific applications
- Hybrid computers are used for controlling industrial processes.
Computers are classified on the basis of computing power, memory capacity and cost.
- Microcomputer or personal computer.
- Mini computer.
- Mainframe computer
- Super computer
Micro Computer
Micro computer is also called personal computer.it was introduced in 1970 examples of personal computers are PC and Apple Macintosh. The major types of personal computers are desktop computer and portable computer.
Desktop Computer
These computers can easily fit on a table or desktop, hence the name. these computers come in two models or casings, in desktop model, the system unit is placed on the desktop or table. Monitor is placed on the system unit. In Tower model both monitor and system unit are placed on the table as in flag 5
Portable Computer
Portable is a personal computer that can be carried form one place to other easily. Notebook computer and handheld computer (smart phone) are examples of portable computer, Notebook computer is also called laptop computers are very small in size and can be placed easily on lap.
Lap top computer or notebook computer
The laptop computer or notebook computer will be as shown in fig 6a and fig 6b. it is also called as tower model computer.
Palmtop computer/ digital Diary/ Notebook/PDAs:
Palmtops have no keyboard but the screen serves both as an input and output device. It easily fits in the hand of the user.
Uses of Micro Computer
The PC is the most common type of computer used in the office, it is now widely used in many homes. These are also used for business and engineering application
Mini Computer
Mini computers were introduced in the 1960s. minicomputer is larger and more powerful computer than personal computer. It can execute five million instructions par second. It generally consists of two or more processors.
Minicomputer can serve up to 4000 connected users simultaneously. It is normally accessed by users via personal computer or terminal. A device with a monitor and keyboard is called terminal. It is also known as dumb terminal. It has no processing power and cannot work as stand-alone computer. Some of the minicomputers models are VAX-8800, AS400
Uses of mini computer
Mini computers are often used by small and medium-sized companies to provide centralized store of information.
Mainframe computer
Mainframe computers were introduced in 1975. A mainframe computer is a very large computer in size. It is processors. It is designed to perform multiple tasks for multiple users at the some time. Mainframe computers can serve up to 50,000 users at the same time.
The users access a mainframe computer through terminal or personal computer. A typical mainframe computer can execute 16 million instructions per second. Some of the main computers models are
NEC610
DEC10
Uses of mainframe computers
Mainframe computers are used primarily by corporate and governmental organizations for critical applications, bulk data processing such as senses, industry and consumer statistics, and transaction processing.
Super computer
Super computer were introduced in 1980s. super computer is the fastest computer, super computer is the biggest in size and the most expensive in price than any other computers.
It is the most sophisticated, complex and advanced computer. It has a very large storage capacity. It can process trillions of instructions in one second. Super computer is the fastest and most powerful computer of a time. Super computers are very expensive Tasks. Super computers are also used for specialized applications that require immense amounts of mathematical calculations.
Applications of super computer
- Weather forecasting,
- Animated graphics line in Hollywood movies,
- Fluid dynamic calculations
- Nuclear energy research
- Space science
- Weapon and missile design
- Petroleum exploration, and etc.
Today, supercomputers are produced by traditional companies such as Cray, IBM and Hewlett- Packard. Since October 2010, the tianhe-1A super computer has been the fastest in the world. It is located in China.
The main difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a single program as fast as possible, whereas a mainframe uses its power to execute many programs concurrently. The modern super computer consists of thousands of microprocessors. Super computer uses high-speed facilities such as satellite for online processing.
Sum of the super computers models are CRAY-XP, ETA-10, Param and Deep Blue.
Advantages of Computers
A computer has a very high processing speed with high reliability.
Large volume of information can be stored in the memory any particular data/program can be retrieved immediately.
Solution to a complicated problem is possible at a very high speed.
Processing of large volume of data saves a lot of clerical work which reduces the processing cost.
Computers perform operations efficiently at environments where presence of human being is not possible such as furnace poisonous atmosphere vacuum unmanned satellite etc.
Limitation of computers
- High initial cost.
- Input information has to be prepared in the form of statements called program which requires a considerable amount of knowledge.
- Usage of computers will be economical only when there is clerical data processing for large volume of data and are repetitive in nature.
- It is a merely a machine it cannot correct errors in its own.
Functions of computers
All computers are made up of following basic units as shown in fig 7 they are as follows:-
- Input unit
- Central Processing unit(CPU)
- Arithmetic Logic Unit(ALU)
- Control Unit(CU)
- Memory
- Output Unit
- Input Unit
Computers need to receive data and instruction in order to solve any problem. therefore we need to input the data and instructions into the computers. The input unit consists of one or more input devices. Keyboard is the one of the most commonly used input device. Some of the input devices are listed in table 1.
Input devices perform the following functions.
- Accept the data and instructions form the outside world.
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- Convert it to a form that the computer can understand.
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- Supply the converted data to the computer system for further processing.
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- Central processing unit(CPU) flg.8
The central processing unit(CPU) is the electronic brain of the computer as in fig 8 the CPU in a personal computer is usually a single chip. It organizes and carries out instructions that come form either the user or form the software. The processor is made up of many components. CPU performs the following functions:
- It performs all calculations.
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- Ti takes all decisions.
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- It controls all units of the computer.
Two typical components of a CPU are the following:-
The arithmetic logic unit(ALU), Which performs arithmetic and logical operations.
The control unit(CU), which extracts instructions form memory and decodes and executes them, calling on the ALU when necessary.
Memory
Memory refers to the physical device used to store the program or data on the temporary or permanent basis for use in a computer ir other digital electronic device.
There are two types of memory in computer.
Primary memory
Secondary memory
Output Unit
Output unit receive the information form the processing unit and provide the results in human readable form.
Output Devices The some of the output devices are
- Monitor
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- Printer
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- Plotter
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- Speaker
Applications of computers Science
Scientists have been using computers to develop theories and to analyse and test the data. The high speed and accuracy of the computer allow different scientific analyses to be carried out. They can be used to generate detailed studies of how earthquakes affect buildings or pollution affects weather pattern. Satellite-based applications have not been possible without the use of computers. Moreover, it would not be possible to get the information of the solar system and the cosmos without computers.
Education:
Computers have also revolutionized the whole process of education. Currently, the classrooms, libraries and museums are efficiently utilizing computers to make the education much more interesting. Unlike recorded television shows, computer-aided education (CAE) and computer-based training(CBT) package are making learning much more interactive.
Medicine and health care:_
There has been an increasing use of computers in the field of medicine. Now, Doctors are using computers right form diagnosing the illness to monitoring a patient’s status during complex surgery. By using automated imaging techniques, doctors are able to look a person’s body and can study each organ in detail(e.g. CT scans or MRI scans),which was not possible few years ago. There are several examples of special-purpose computers that can operate within the human body such as cochlear implant, a special kind of hearing aid that makes it possible for deaf people to hear.
Engineering/Architecture/Manufacturing
The architects and engineers are extensively using computers in designing and drawings. Computer can create objects that can be viewed from all the three dimensions. By using techniques like virtual reality, architects can explore houses that have been designed but not built. The manufacturing factories are using computerized robotic arms to perform hazardous jobs besides, computer-aided manufacturing(CAM) can be used in designing the product, ordering the parts and planning production. Thus, computers help in coordinating the entire manufacturing process.
Entertainment:
Computers are finding greater use in entertainment industry. They are used to control the images and sounds. The special effects, which mesmerize the audience, would not have been possible without the computers. In addition, computerized animation and colourful graphics have modernized the film industry.
Communication:-
E-mail or electronic mail is one of the communication media in which computer is used. Through e-mail, messages and reports are passed form one person to one or more persons with the aid of computer and telephone line. The advantage of this service is that while transferring the messages it saves time, avoids wastage of paper and so on. Moreover, the person who is receiving the messages can read the messages whenever he is free and can save it reply it forward it or delete it form the computer.
Business Application
This is one of the important uses of the computer. Initially, computer were used for batch-processing jobs, where one does not require the immediate response form the computer. Currently, computer are mainly used for real-time applications(like at the sales counter) that require immediate response form the computer. There are various concerns where computers are used such as in business forecasting, to prepare pay bills and personal records, in banking operations and data storage in various types of life insurance business and as an aid to management. Businesses are also using the networking of computers, where a number of computers are connected together to share the data and the information. Use of e-mail and the internet has changed the ways of doing business.
Publishing:
Computers have created a field known as desktop publishing(DTP). In DTP, with the help of computer and a laser printer one can perform the publishing job all by oneself. Many of the tasks requiring long manual hours such as making table of contents and index can be automatically performed using the computers and DTP software.
Banking:
Computers are extensively used in the field of banking and finance. People can use the ATM(Automated Teller Machine) services 24 hours a day to deposit and withdraw cash. When different branches of the bank are connected through computer networks, the inter branch transactions such as cheque and draft can be performed without any delay.
Railway Reservation System
Using this system, the user can perform following operations through online.(web site : www.irctc.co.in)
- Search the train and its timings.
- Check seats and birth availability.
- Booking and cancelling tickets.
- Status of PNR(Passenger Name Record)
- Telephone / Electricity Board Billing:
The users can do the following operations through online by using this system.(Web site : portal.bsnl.in- BSNL)
- Register the telephone/ electricity board number
- Check and pay the bill amount
- Register the complaints
E-Governance
E-Governance implies technology driven governance. E-Governance is the application of information and communication technology(ICT) for delivering government services, Exchange of information communication transactions, integration of various standalone systems and services between Government-To-Citizens(G2C),Government-To-Business(G2B),Government-To-Government(G2G) as well as back office processes and interactions within the entire government frame work.
E-Government covers all the sectors with a view to providing hassle free, transparent and efficient service to the common man (both in urban and rural areas).
