Classification of Computers

Computers are classified based on their capacities and uses. The major classification of computer are

·        On the basis of work

·        On the basis of size

·        On the basis of brand

·        On the basis of model

Brand

Size

Work

Model

XT AT PS/2

IBM PC IBM Compatible Apple/Macintosh

Micro Mini Mainframe Super

Analog Digital Hybrid

Classification of Computers

 

On the basis of Work

Analog Computer: -Computer is one which operates on continuous data usually a physical quantity such as temperature, electrical, mechanical, hydraulic, pressure etc. It is a special purpose computer, dedicated to a single task. It is widely used in scientific and industrial application. Analog computers recognize data as continuous measure of physical property (voltmeter, pressure, temperature).

Example: Plesley, Seismography, speedometer, Thermometer, voltmeter, pressure gauge, odometer, ammeter, barometer, lactometer etc.

Digital Computer: A digital computer is an electronic computing machine that uses the binary digits (bits) 0 and 1 to represent all forms of information in digital form. These are high speed programmable electronic device that perform mathematical calculations, compares values and store results. They recognize data by counting discrete signal representing either high or low. In digital computer, even letters, words and whole text are represented digitally. It is a general purpose device, dedicated to a multiple task.  Example IBM PC, Apple/Macintosh computer

Difference between Analog and Digital computer

Analog Computer	Digital Computer
1.      Analog computer measures the continuous physical variations such as pressure, temperature, voltage etc.	1.      Digital computer processes discrete data such as number, letters etc.
2.      It generates analog signals	2.      It generates digital signal
3.      It has very low accuracy	3.      It has high accuracy
4.      It has high cost	4.      It has low cost.
5.      It is used for special purpose	5.      It is used for general purpose
6.      Re-programmed is not possible	6.      Re-programmed can be possible
7.      It is  based on similarity measurement principle	7.      It is based on counting principle
8.      It is faster than digital computer	8.      It is slower than analog computer
9.       It has  no or limited storage capacity	9.      It has high storage capacity
10.   It does singe purpose job	10.   It does multipurpose job
11.   Is is stored in the form of wave signal	11.   It is stored in the form of binary bit
12.   Analog signal processing can be done in real  time  and consumes less bandwidth.	12.   There is no guarantee that digital signal processing can be done in real time and consumes more bandwidth to carry out same information.
13.   E.g. Speedometer, Seismograph, Plesley	13.   E.g. IBM PC, IBM Compatible,, Apple/Macintosh

Hybrid Computer: Computer that contains the features of both analog computers and digital computer that are capable of inputting and outputting in both analog and digital signal. Example FMC (Flight Management Computer), EICS, aero planes, jet planes, industries, ICU (Intensive Care Unit) in hospital etc.

Characteristic of hybrid computer: -

i)         It combines the best qualities of analog and digital computer.

ii)       It can process both continuous and discrete data

iii)      It can convert one type of data into another.

iv)      These computers are mostly used in areophane, hospital, industries etc.

v)        It is expensive.

vi)      These computes are mostly used in hospital to measure heard beat of patient

Classification on the basis of size: - computers on the basis of size or volume are classified as following types

Super computer: -Super computer are the largest, fastest and most expensive computers. The have lager memory capacity and very high processing speed. The are 64-bit system with 100 MIPS (Millions of Instruction per second) speed and 8 MB storage capacity. They are used for solving very large and complex problems within a Nanoseconds. It is multiuser, multiprocessor large computer with a very high efficiency and storing capacity. Example are CRAY-XMP/14, CDC-205, CYBER 205, ETA 10 etc.

 Application of supercomputer

Aerospace industry: - to simulate airflow around an aircraft at different speed and altitude.

Automobile industry: - design of an automobile and to do crash simulation.  

Structural mechanic: to solve structural engineering problems to ensure safety, reliability and cost effectiveness.

Petroleum industry: - to analyze data about petroleum product inside the earth.

Weapons research

Encrypting and decrypting sensitive intelligence information.

Scientific computing and research

Weather forecasting: Meteorological centers use supercomputer for weather forecasting.

Biomedical research- atomic nuclear and plasma analysis, to study the structure of viruses.

Mainframe computer: - Mainframe computer are the computers with large storage capacities and very high speed of processing that support large amount of terminals for simulations use by number of users. Mainframe computer will have a very powerful processor, large amount of main memory and huge backing storage capacity. They are used in banking, airline, railways, educational institution, insurance companies etc. They are also called Enterprise Server. Example IBM1401, ICL 2959/10, IBM S/390 etc.

Characteristic

1.      They are very large in size with large storage capacity and high processing speed.

2.      They support large number of terminals approximately 100.

3.      It is general purpose computer.

4.      Consist of multiple processor, GB of memory and TB of storage,

5.      They can run multiple operating system. Hence they are called virtual machine.

Application: - used for process large amount of data at very high speed such as in bank/insurance companies, hospitals, railways,

Used to controlling node in WAN

Used to manage large centralized database.

Minicomputer:-Minicomputer is a general purpose computer which is comparatively small and less expensive than a mainframe computer. It has slowest operation speed, smaller vacuum storage, limited hardware and lesser memory capacity compared to a mainframe computer. They are used by small business and firms. Minicomputer are also called midrange system or workstations. Example IBM, HP-9000, PDA-II etc.

Characteristics

·        There are medium sized computers.

·        They support small number of terminals approximately 50.

·        They are general purpose computer.

·        They can process more data can can support more I/O devices.

·        They are less powerful than mainframe computers but more powerful than microcomputers. Hence they are called midrange computers.

·        They are used in business as a centralized computer or as an internet server.

·        They are less expensive than mainframe computer and more expensive than microcomputer.

·        They are used in medium sized organizations.

Microcomputer: - A microcomputer is the smallest general purpose processing system based on microprocessor or chip. It consists of a CPU in a single which supports storage of a much smaller scale like hard disk or floppy disk, it can be used by a single person at a time. Microcomputer are also called personal computer. the peripheral device used in microcomputer are keyboard, magnetic disk, monitor, printer, mouse, etc.

Microcomputer are used in wide range like general purpose calculation, teaching, industrial control, office automation and business communication. Example PC of IBM, Apple/Macintosh

Characteristics of microcomputers are

                 I.          They are smallest in size.

               II.          They are based on microchips.

             III.          Though they are small in size, some microcomputers has high storage and processing capacity.

            IV.          It supports may higher level language.

              V.          It supports multimedia

            VI.          It supports multimedia.

          VII.          It supports graphic, 3D graphic and games.

        VIII.          It supports networking.

            IX.          It supports new features of input and output devices

              X.          It supports different types of operating system like as GUI and CUI.

Difference between Mini and microcomputers.

Mini Computer	Micro computer
They are more powerful than micro computers	They are less powerful than mini computer
They are comparatively more expensive	They are comparatively cheaper
They are bigger in size so that nearly 50 terminals can work	They are smaller in size and can work only single  terminal;
They are not general purpose	They are general purpose computers.
Example IBM, HP-9000, PDA-II etc.	Example : PC of IBM, Apple/Macintosh

On the basis of brand

IBM PC (IBM Personal Computer): - The computer developed by International Business machine company (IBM) are called IBM PCs. IBM company was developed in 1924. In 1945, IBM company stated manufacturing digital computer. IBM computer are more reliable, durable and have better quality. It was specifically design for professional and scientific problem solvers.

IBM Compatible Computer: - IBM compatible computers are developed by other than IBM companies using the technology of IBM PC. They have the same functional and operational characteristic of IBM PC. All the program used in IBM are compatible with IBM compatible so they are called as duplicate of IBM.  They are cheap, easily available, Example Compaq, NEC (Nippon electronic,) ALR (Advance Logic Research), AST, SCAN, IT 2000 etc.

Apple/ Macintosh Computer: - Apple computers are developed by Apple Corporation which was established in late 1970s, in the USA. Apple Corporation developed a most popular microcomputer named Macintosh. This computer is mainly used for desktop publishing work. Apple cost are costlier the IBM computer. They are available in different capacity, cost and sizes.

Different between IBM PC and IBM Compatible computers

IBM PC	IBM Compatible
1.      They are original and banded computes manufactures by IBM company itself	1.      They are duplicated and assembled computers developed by local company with the permission of IBM company
2.      They are more expensive	2.      They are cheaper then IBM PC
3.      They are comparatively stronger	3.      They are comparatively less strong
4.      They use original and genuine software	4.      They use genuine and pirated software both
5.      They are more reliable then IBM compatible	5.      They are less reliable than IM PCs.
6.      It was specially designed for professionals and scientific problem solvers.	6.      It was designed for general user and their parts are easily available in market.

Difference between IBM PC and Apple Macintosh

IBM PC	Apple/Macintosh
1.      These computers use both GUI and CUI programs	1.      These computers use only GUI program
2.      They are manufactures by IBM company USA	2.      They are manufactured by apple corporation USA
3.      Mouse or pointing input device is optional to these computers	3.      Mouse or pointing input device is compulsion to the computers
4.      In IBM PC the VDU and CPU are separated	4.      In apple ,/Macintosh computes the VDU and CPU are attaches together.
5.      In IBM PCs, the mouse is connected to CPU	5.      In Apple/Macintosh computers, the mouse is connected to  keyboard
6.      They are comparatively less expensive	6.      They are comparatively more expensive.

Personal Computer: - A personal computer is a single user oriented and general purpose micro computer processing system that can execute the program instruction to perform a wide variety of task.  A personal computer contains a monitor, keyboard; mouse etc. high level language can be used in a personal computer. Operating system such as Microsoft Windows, Linux and UNIX are used in thus type of computer system.

Types of Personal Computers

Desktop computer: Desktop computers are the single user personal computers that can be placed on the desktop. Desktop computer contains primary memory (RAM, ROM) and secondary storage like hard disk, magnetic tape, CD/DVD ROM etc. peripheral devices such as monitor, keyboard, mouse etc are attached with it. It is used for desktop publishing, graphics, data entry, entertainment etc.

Laptop computer:  Laptops computer are portable computer and the size of a laptop computer can easily fir in a briefcase. Laptop computers are very light in weight, small in size and flat design. A laptop contains attached keyboard, a flat LCD display, a touch pad, CD/DVD derive etc. Laptop computer normally runs Microsoft Windows, Linux, and UNIX etc.

Handheld computer: A hand held computer is a device whose size, weight and design are such that it can be used comfortably by holding in hand. It is also known as palmtop because it can be kept on palm and operated. Some popular and held computers are tablets PC, PDA/Pocket PC and smart phones.

On the Basis of Model

XT Computer (Extended technology): The computer which uses 8086 or 8088 microprocessor and having processing speed 4.77 MHZ. It is comparatively slower and less flexible than other model. It cannot support GUI based program and software.

AT computer: The computer which uses 80286, 80386, 80846 or 80586 series of microprocessor is known as AT computer. At computer are faster than XT computer. Its processing speed and memory capacity is also larger than XT.

PS/2 (Personal System-2): - These type of computer came in the market after 1990 manufactured by IBM company. These models of computer are faster and efficient that AT modern and based on refined architectural design.

Mobile Computing: It is the process or method of using portable computing technology that allows to use and access internet and other application services when we are on move. Small and portable handheld computing devices and advanced mobile phone are popularly used.  

Mobile computing has three aspects mobile communication, mobile hardware and mobile software. The first aspect addresses communications issues in ad-hc and infrastructure networks as well as communication properties, protocol, data format and concrete technologies. The second aspect is on the hardware e.g. mobile devices or device computers. The third aspect deals with the characteristics and requirements of mobile applications. There are different types of mobile computing device such as personal digital assistance(PDA), smart phone, blackberry phone, iPhone, internet tablets, HSPDA (High Speed Packet Data Access) and other 3G mobile etc.