All computer system contain hardware components for data input , processing and out put . Computer mainly contain electronic components , namely transistors and ICs ( Integrated Circuits ) etc , and these components are connected with each other to form computer circuits . Software are stored programs which run on computer hardware to achieve desired result .  Computer can be classified according to thair .

A>> Application

B>> purpose

C>> size

A>>  Application :  

  Computers can be used to count number or to measure physical quantities . There can be three broad categories of computers as :

@  Digital computer

@  Analog computer

@  Hybrid computer  

~~>>  Digital computer : It operates on data which is in the form of bits ( binary digits ) . Input to digital computer is supplied in group of bits , called word . Group of bits represents numerals , latters or other special symbols as per the ASC|| ( American Standard Code For Information Interchange ) table . the input is discrete and a digital signal . Most of the present day computer are Digital Computer .

~~>>  Analog Computers :  These computers measures physical values such as temperature , pressure , flow of oil etc. These are Widely used in manufacturing units where temperatur , pressure , current , voltage etc are to be measured continuously . Example : An analog computer at a petrol pump can be used to measure the flow of petrol . Analog computers have many limitations such as :  

>>  These are not able to store large data .  

>>  Logical facilities available are quite limited .  

>>  Arithmetic operations have little accuracy .

~~>>  Hybrid Computers : Features of analog computers and digital computers are combined in Hybrid Computers . A hybrid computer used Analog - to - digital converter and Digital - to - analog converter . It accepts input in the form of continuously varying input , which is then converted into digital data ( discrete data ) and then process it to produce results . Conversion from analog data to digital data is done because digital signal processing is fast and more accurate . A hybrid computer is suitable in Real Time Applications . but they have very limited applications.

B>> Purpose :

According to thair purpose computer can be of two types :

1 >>  General Purpose Computer .

2 >>  Special Purpose Digital Computer .

1>> General Purpose Computer : It is a multi - purpose or all - purpose type of a computer . It can be used in larg variety of applications such as graphical , analytical , mathematical , commercial , web based etc. A personal computer ( P.C. ) is a general purpose digital computer .

2>> Special Perpose Digital Computer : It is designed to solve some specific problem . Example : A computer designed to count and check quality of fountain pens in a pen menuacturing industry

C>>  Size :

  Large system have greater processing speed , more storage capacity , high cost and they can handle large number of input and output devices . They can provide services to many user at the same time . Whereas the smaller system are used by single user ( one person at a time ) . According to thair size , computers can be broadly classified as :

@ >>  Micro Computers :

  These are low - end small size computers . Personal computer ( PCs ) and Laptop computer ( Notebook computer ) are in the category of micro - computers . These are low cost machines suitable for small business & scientific applications . A PC has less storage capacity , less processing power and less speed than mini - computer . A PC now - a - days has RAM of 512 MB , Hardisk of 80 GB capacity and CPU speed approximately 3.0 GHz .

@ >>  Mini computers :

  These are small general purpose computer system on which many user can work at the same time . These are more powerful and expensive than micro - computer system . About 4 to 32 user can work simultaneously on a mini - computer . Large number of peripheral devices , such as printers , plotters etc . can be connected to a mini computer . They are generally used in payroll preparation , scientific computations , graphical applications such as Geographical Information Systems ( GIS ) .

@ >>  Mainframe computers :

  These system have faster processing speed and greater capacity than mini - computers . These are expensive machnes and mainly used to solve complex problems . They are generally used in research organizations , large industrial houses , airline and railway booking network , insurance companies etc . They have the capability to execute computer programs written various computer language .

@ >>  Super computers :

  These are fastest and most expensive computer systems . They are multiprocessor systems and can handle large number complex problems at the same time . Theseare generally used in research organization , missile  development programs , aircraft designs, weather forecasting , remote sensing , space applications etc .CRAY - 1 , CRAY - 2 are the initial super computers developed in USA . India has also started manufacturing super computers and PARAM was the first Indian super computer developed by CDAC , pune .