Classification of computer
- 1. 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
- 2. According to functionAccording to function According to function computers can beAccording to function computers can be classified into four types. Theseclassified into four types. These classification of computer based onclassification of computer based on principle of operation and hardwareprinciple of operation and hardware structure.structure. Digital ComputerDigital Computer Analog ComputerAnalog Computer Hybrid ComputerHybrid Computer
- 3. Digital ComputerDigital Computer A Digital computer works with data in term ofA Digital computer works with data in term of discrete number or digit. These number arediscrete number or digit. These number are used to perform, arithmetic calculations andused to perform, arithmetic calculations and also make logical decision to reach aalso make logical decision to reach a conclusion depending on the data theyconclusion depending on the data they receive from the user. All the expressionsreceive from the user. All the expressions are coded into binary digits (0 and 1) insideare coded into binary digits (0 and 1) inside the computer and it manipulates them atthe computer and it manipulates them at very fast speed.very fast speed.
- 4. A digital computer manipulates dataA digital computer manipulates data according to the instructions oraccording to the instructions or programme given to it in a certainprogramme given to it in a certain computer language.computer language. The instructions and data are fed to theThe instructions and data are fed to the computer in the form of discrete electricalcomputer in the form of discrete electrical signals. Digital Computers are easy tosignals. 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.
- 5. Analog ComputerAnalog Computer Analog computers actually is a measuringAnalog computers actually is a measuring device. An analog computer measuresdevice. An analog computer measures continues type of data and use a physicalcontinues 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 firstweight etc. Analog Computers are the first Computers being developed & provide theComputers being developed & provide the base for the development of modernbase for the development of modern digital computers. These computers aredigital computers. These computers are mainly made of electrical devices likemainly made of electrical devices like resisters, amplifiers & transistors.resisters, amplifiers & transistors.
- 6. This machine has a very limited memory & canThis machine has a very limited memory & can perform only certain type of calculations, whichperform only certain type of calculations, which make it specialized machine, suitable formake it specialized machine, suitable for engineering & scientific calculations. An analogengineering & scientific calculations. An analog computer is basically a device for solvingcomputer is basically a device for solving ordinary differential equations and can be usedordinary differential equations and can be used in solution in solution of those problems whichin solution in solution of those problems which can be converted to ordinary differentialcan be converted to ordinary differential equations. In general, Analog computer areequations. In general, Analog computer are very fast in processing because all thevery fast in processing because all the
- 7. operations performed in this machine areoperations performed in this machine are parallel but accuracy of these machines isparallel but accuracy of these machines is quite low. Speedometer and millimeterquite low. Speedometer and millimeter (used in vehicles), Electric meter & Gas(used in vehicles), Electric meter & Gas meter (fixed on the supply line of themeter (fixed on the supply line of the house) pressure gauges & thermometershouse) pressure gauges & thermometers are the general example of the analogare the general example of the analog devices.devices.
- 8. Hybrid ComputerHybrid Computer A Hybrid computer is, which combines theA Hybrid computer is, which combines the analog & digital capabilities in the sameanalog & digital capabilities in the same computer system. Hybrid computers helpcomputer system. Hybrid computers help the user to exploit the machine's ability tothe user to exploit the machine's ability to process both continuous and discreteprocess both continuous and discrete data. These machines are generally useddata. These machines are generally used for scientific applications & it is also usedfor scientific applications & it is also used as a controlling device in an industrialas a controlling device in an industrial process.process.
- 9. The results can be obtained either asThe 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 ofeither as continuous output in the form of graph discreet digits. This result can begraph discreet digits. This result can be obtained by an electronic deviceobtained 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 signalstransform analog signals to digital signals and vice versa.and vice versa.
- 10. According to purpose.According to purpose. Computer can be classified according toComputer can be classified according to purpose in two ways.purpose in two ways. General PurposeGeneral Purpose Special PurposeSpecial Purpose 1.1. General Purpose: These computer areGeneral Purpose: These computer are designed to solve wide variety of problemsdesigned to solve wide variety of problems from different fields. The hardware and thefrom different fields. The hardware and the software of such system are adaptable totallysoftware of such system are adaptable totally different environments. These Computer aredifferent environments. These Computer are used for different purpose like inventoryused for different purpose like inventory Control, Record keeping , Accounting, payrollControl, Record keeping , Accounting, payroll etc.etc.
- 11. 2. Special Purpose:2. Special Purpose: As the name suggestsAs the name suggests these computers system are used only forthese computers system are used only for specific purposes or application. Thesespecific purposes or application. These special purpose computer system may bespecial purpose computer system may be defined as a stored programme computer,defined as a stored programme computer, whose architecture is oriented towards onewhose architecture is oriented towards one or more specific applications. Theseor more specific applications. These computers handle a very narrow categoriescomputers handle a very narrow categories of data processing activities. Some exampleof data processing activities. Some example of special purpose computer with their areaof special purpose computer with their area of application are as fallows.of application are as fallows.
- 12. 1.1. Computer used for Process Control in anComputer used for Process Control in an industry.industry. 2.2. Bio-medical X-ray instrument used only forBio-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 test 4.4. CCG machine which is used for CCG testCCG machine which is used for CCG test 5.5. Electronic digital blood pressure instrumentElectronic digital blood pressure instrument 6.6. Computer system used for desktopComputer system used for desktop publishingpublishing 7.7. 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.
- 13. According CapabilitiesAccording Capabilities According to capabilities computers couldAccording to capabilities computers could easily be classified into minis, microseasily be classified into minis, micros mainframes and super by considering theirmainframes and super by considering their size, performance and cost. However, todaysize, 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 commondue to the ever increasing pace of common usage altogether. The manufactures are notusage altogether. The manufactures are not helping by bringing out many terms such ashelping by bringing out many terms such as mini super minis and micro mainframes etc.mini super minis and micro mainframes etc.
- 14. These are obviously terms used toThese are obviously terms used to describe the approximate position in thedescribe 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 stillTo understand this mass of jargon, it is still necessary to understand the oldernecessary to understand the older definitions of the terms minis , micros,definitions of the terms minis , micros, mainframes and super, now we will discusmainframes and super, now we will discus these computers in detail the following.these computers in detail the following.
- 15. MicrocomputerMicrocomputer This is quite simply, a computer which uses aThis 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 basiccomplex chip which contains most of the basic systems need to set up a computer systemsystems need to set up a computer system using this single chip as the centralusing this single chip as the central processing unit. In the late 1970s the firstprocessing 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. Thismicroprocessors were available earlier. This meant that their fundamental unit of data wasmeant that their fundamental unit of data was eight binary digits.eight binary digits.
- 16. MinicomputerMinicomputer Thin is a medium-sized computer and canThin is a medium-sized computer and can vary in power from a very large and powerfulvary 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 considerablymainframes market has shrunk considerably over the last few years. A minicomputer isover the last few years. A minicomputer is often a floor-standing model, although someoften a floor-standing model, although some modem ones now fit onto the top of yourmodem ones now fit onto the top of your desk- but there is not much space left for thedesk- but there is not much space left for the coffee pot !coffee pot !
- 17. A small minicomputer might be able toA 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 singletherefore, 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 theThey are really mini versions of the mainframe computer, and this is wheremainframe computer, and this is where the term mini was originally coined. Thethe term mini was originally coined. The mini has been designed with multi-usermini has been designed with multi-user access in mind & is therefore usuallyaccess in mind & is therefore usually easy to expand up to maximum possibleeasy to expand up to maximum possible numbers of a users.numbers of a users.
- 18. Mainframe computersMainframe computers These are the largest of computerThese are the largest of computer systems (not necessarily the fastest orsystems (not necessarily the fastest or most powerful)- they certainly will not fit onmost powerful)- they certainly will not fit on the top of your desk ! It is common to havethe top of your desk ! It is common to have hundreds of simultaneous users on such ahundreds of simultaneous users on such a system. There is usually a vast amount ofsystem. There is usually a vast amount of RAM, and any extra peripherals such asRAM, and any extra peripherals such as tape & disk machines.tape & disk machines.
- 19. Super computersSuper computers There are the fastest & most expensiveThere are the fastest & most expensive modern computer systems. They are usuallymodern computer systems. They are usually not used for normal data processing, but fornot used for normal data processing, but for intense mathematical calculations such asintense mathematical calculations such as forecasting the weather, or super highforecasting the weather, or super high resolution graphics such as ray-tracedresolution graphics such as ray-traced images. Nevertheless, for very large systemsimages. Nevertheless, for very large systems such as the customs-clearance system in thesuch as the customs-clearance system in the port of a development country, all theport of a development country, all the government departments are linked to agovernment departments are linked to a super-computer which is then able tosuper-computer which is then able to
- 20. produce all the necessary documentationproduce all the necessary documentation for clearance in just a few minutes,for clearance in just a few minutes, compared to several days under the oldercompared 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 requireengineering applications which require enormous processing speed & power.enormous processing speed & power.