Classification of computerClassification of computer

Computers can be classified as follows.Computers can be classified as follows.

1.1. According to functionAccording to function

2.2. According to purposeAccording to purpose

3.3. According to capabilitiesAccording to capabilities

According to functionAccording to function

According to function computers can be According to function computers can be classified into four types. These classified into four types. These classification of computer based on classification of computer based on principle of operation and hardware principle of operation and hardware structure.structure.

Digital ComputerDigital Computer Analog ComputerAnalog Computer Hybrid ComputerHybrid Computer

Digital ComputerDigital Computer

A Digital computer works with data in term of A Digital computer works with data in term of discrete number or digit. These number are discrete number or digit. These number are used to perform, arithmetic calculations and used to perform, arithmetic calculations and also make logical decision to reach a also make logical decision to reach a conclusion depending on the data they conclusion depending on the data they receive from the user. All the expressions receive from the user. All the expressions are coded into binary digits (0 and 1) inside are coded into binary digits (0 and 1) inside the computer and it manipulates them at the computer and it manipulates them at very fast speed. very fast speed.

A digital computer manipulates data A digital computer manipulates data according to the instructions or according to the instructions or programme given to it in a certain programme given to it in a certain computer language. computer language.

The instructions and data are fed to the The instructions and data are fed to the computer in the form of discrete electrical computer in the form of discrete electrical signals. Digital Computers are easy to signals. Digital Computers are easy to program and are in general purpose use. program and are in general purpose use. Almost all personal computers (PCs) Almost all personal computers (PCs) belong to this category.belong to this category.

Analog ComputerAnalog Computer

Analog computers actually is a measuring Analog computers actually is a measuring device. An analog computer measures device. An analog computer measures continues type of data and use a physical continues type of data and use a physical quantity, such as electric current, speed, quantity, such as electric current, speed, weight etc. Analog Computers are the first weight etc. Analog Computers are the first Computers being developed & provide the Computers being developed & provide the base for the development of modern base for the development of modern digital computers. These computers are digital computers. These computers are mainly made of electrical devices like mainly made of electrical devices like resisters, amplifiers & transistors. resisters, amplifiers & transistors.

This machine has a very limited memory & can This machine has a very limited memory & can perform only certain type of calculations, which perform only certain type of calculations, which make it specialized machine, suitable for make it specialized machine, suitable for engineering & scientific calculations. An analog engineering & scientific calculations. An analog computer is basically a device for solving computer is basically a device for solving ordinary differential equations and can be used ordinary differential equations and can be used in solution in solution of those problems which in solution in solution of those problems which can be converted to ordinary differential can be converted to ordinary differential equations. In general, Analog computer are equations. In general, Analog computer are very fast in processing because all thevery fast in processing because all the

operations performed in this machine are operations performed in this machine are parallel but accuracy of these machines is parallel but accuracy of these machines is quite low. Speedometer and millimeter quite low. Speedometer and millimeter (used in vehicles), Electric meter & Gas (used in vehicles), Electric meter & Gas meter (fixed on the supply line of the meter (fixed on the supply line of the house) pressure gauges & thermometers house) pressure gauges & thermometers are the general example of the analog are the general example of the analog devices. devices.

Hybrid ComputerHybrid Computer

A Hybrid computer is, which combines the A Hybrid computer is, which combines the analog & digital capabilities in the same analog & digital capabilities in the same computer system. Hybrid computers help computer system. Hybrid computers help the user to exploit the machine's ability to the user to exploit the machine's ability to process both continuous and discrete process both continuous and discrete data. These machines are generally used data. These machines are generally used for scientific applications & it is also used for scientific applications & it is also used as a controlling device in an industrial as a controlling device in an industrial process. process.

The results can be obtained either as The results can be obtained either as analog signal or discrete signal e.g., analog signal or discrete signal e.g., either as continuous output in the form of either as continuous output in the form of graph discreet digits. This result can be graph discreet digits. This result can be obtained by an electronic device obtained by an electronic device ‘MODEM’. A modem is a device which can ‘MODEM’. A modem is a device which can transform analog signals to digital signals transform analog signals to digital signals and vice versa.and vice versa.

According to purpose.According to purpose.

Computer can be classified according to Computer can be classified according to purpose in two ways.purpose in two ways.

General Purpose General Purpose Special PurposeSpecial Purpose1.1. General Purpose: These computer are General Purpose: These computer are

designed to solve wide variety of problems designed to solve wide variety of problems from different fields. The hardware and the from different fields. The hardware and the software of such system are adaptable totally software of such system are adaptable totally different environments. These Computer are different environments. These Computer are used for different purpose like inventory used for different purpose like inventory Control, Record keeping , Accounting, payroll Control, Record keeping , Accounting, payroll etc.etc.

2. Special Purpose:2. Special Purpose: As the name suggests As the name suggests these computers system are used only for these computers system are used only for specific purposes or application. These specific purposes or application. These special purpose computer system may be special purpose computer system may be defined as a stored programme computer, defined as a stored programme computer, whose architecture is oriented towards one whose architecture is oriented towards one or more specific applications. These or more specific applications. These computers handle a very narrow categories computers handle a very narrow categories of data processing activities. Some example of data processing activities. Some example of special purpose computer with their area of special purpose computer with their area of application are as fallows.of application are as fallows.

1.1. Computer used for Process Control in an Computer used for Process Control in an industry.industry.

2.2. Bio-medical X-ray instrument used only for Bio-medical X-ray instrument used only for X-ray.X-ray.

3.3. ECG machine which is used for ECG testECG machine which is used for ECG test4.4. CCG machine which is used for CCG testCCG machine which is used for CCG test5.5. Electronic digital blood pressure instrumentElectronic digital blood pressure instrument6.6. Computer system used for desktop Computer system used for desktop

publishingpublishing7.7. Computer used for air-traffic control.Computer used for air-traffic control.8.8. Computer system which is used in Robots.Computer system which is used in Robots.

According Capabilities According Capabilities

According to capabilities computers could According to capabilities computers could easily be classified into minis, micros easily be classified into minis, micros mainframes and super by considering their mainframes and super by considering their size, performance and cost. However, today size, performance and cost. However, today these definitions are not so cut and dried, these definitions are not so cut and dried, due to the ever increasing pace of common due to the ever increasing pace of common usage altogether. The manufactures are not usage altogether. The manufactures are not helping by bringing out many terms such as helping by bringing out many terms such as mini super minis and micro mainframes etc. mini super minis and micro mainframes etc.

These are obviously terms used to These are obviously terms used to describe the approximate position in the describe the approximate position in the hierarchy to which their products belong. hierarchy to which their products belong. To understand this mass of jargon, it is still To understand this mass of jargon, it is still necessary to understand the older necessary to understand the older definitions of the terms minis , micros, definitions of the terms minis , micros, mainframes and super, now we will discus mainframes and super, now we will discus these computers in detail the following.these computers in detail the following.

Microcomputer Microcomputer This is quite simply, a computer which uses a This is quite simply, a computer which uses a microprocessor is the name given to the very-microprocessor is the name given to the very-complex chip which contains most of the basic complex chip which contains most of the basic systems need to set up a computer system systems need to set up a computer system using this single chip as the central using this single chip as the central processing unit. In the late 1970s the first processing unit. In the late 1970s the first Microcomputers were 8-bit machines. Microcomputers were 8-bit machines. (although some less-useful 4-bit (although some less-useful 4-bit microprocessors were available earlier. This microprocessors were available earlier. This meant that their fundamental unit of data was meant that their fundamental unit of data was eight binary digits. eight binary digits.

MinicomputerMinicomputer

Thin is a medium-sized computer and can Thin is a medium-sized computer and can vary in power from a very large and powerful vary in power from a very large and powerful micro to a small mainframes. Indeed, micro to a small mainframes. Indeed, because of the increasing power of minis, because of the increasing power of minis, mainframes market has shrunk considerably mainframes market has shrunk considerably over the last few years. A minicomputer is over the last few years. A minicomputer is often a floor-standing model, although some often a floor-standing model, although some modem ones now fit onto the top of your modem ones now fit onto the top of your desk- but there is not much space left for the desk- but there is not much space left for the coffee pot ! coffee pot !

A small minicomputer might be able to A small minicomputer might be able to support b/w ten & twenty users. It is , support b/w ten & twenty users. It is , therefore, ideal for use-within a single therefore, ideal for use-within a single department within a college or university, department within a college or university, or far use in a medium size business. or far use in a medium size business. They are really mini versions of the They are really mini versions of the mainframe computer, and this is where mainframe computer, and this is where the term mini was originally coined. The the term mini was originally coined. The mini has been designed with multi-user mini has been designed with multi-user access in mind & is therefore usually access in mind & is therefore usually easy to expand up to maximum possible easy to expand up to maximum possible numbers of a users.numbers of a users.

Mainframe computersMainframe computers

These are the largest of computer These are the largest of computer systems (not necessarily the fastest or systems (not necessarily the fastest or most powerful)- they certainly will not fit on most powerful)- they certainly will not fit on the top of your desk ! It is common to have the top of your desk ! It is common to have hundreds of simultaneous users on such a hundreds of simultaneous users on such a system. There is usually a vast amount of system. There is usually a vast amount of RAM, and any extra peripherals such as RAM, and any extra peripherals such as tape & disk machines. tape & disk machines.

Super computersSuper computersThere are the fastest & most expensive There are the fastest & most expensive modern computer systems. They are usually modern computer systems. They are usually not used for normal data processing, but for not used for normal data processing, but for intense mathematical calculations such as intense mathematical calculations such as forecasting the weather, or super high forecasting the weather, or super high resolution graphics such as ray-traced resolution graphics such as ray-traced images. Nevertheless, for very large systems images. Nevertheless, for very large systems such as the customs-clearance system in the such as the customs-clearance system in the port of a development country, all the port of a development country, all the government departments are linked to a government departments are linked to a super-computer which is then able tosuper-computer which is then able to

produce all the necessary documentation produce all the necessary documentation for clearance in just a few minutes, for clearance in just a few minutes, compared to several days under the older compared to several days under the older manual systems. manual systems.

There are also many complex scientific & There are also many complex scientific & engineering applications which require engineering applications which require enormous processing speed & power.enormous processing speed & power.