5)On the basis of brand
On the basis of brand computer can be classified as:

i) IBM
The computer that are manufactured by IBM are known as IBM PC.IBM PC is one of the leading company of the world in manufacyuring computers.These are more reliable ,durable & have better quality.It was also very expensive in comparision to IBM compatible computer.It was specifically designed for professional & scientific problem solves.

ii) IBM Compatible
The computers that are manufactured by other companies but having same technology & fetures of IBM PC are known as IBM Compatible.such computers are refer to as Pc clones or IBM clones.Since they almost exactly duplicated all significant features of PC architecture facilated by various manufactures.

iii)Apple Mac
the computers that are manufactured by Apple Mac company but having different architecture & configuration then IBM compatibles are known as Apple Mac.They have system produced by Apple company for their maintosh is called Mac OS.




) 6) On the basis of model

i) XT(Extra Technology)
The computers having 8000 ,8086 ,8088 microprocessor & processing speed of 4.TT mega hertz are known as XT.It can’t support GUI (Graphics User Interfare) based operating system.

ii) AT
The computer having 80286 ,80386 ,80486 ,Pentium-I Pentium-II & Pentium-IV microprocessor & processing speed.

iii) PC 12
It is a laptop computer with rechargeable battery based system.It is operated with OC1R operating system.These computers are use refinal architecture making the computer faster than AT computer.They can almost all programe.eg:laptop hand held computer.

Number system.

1. Decimal (0-9)10
2. Binary (0-1)2
3. Octal (0-7)8
4. Hex (0- )

Today we can’t imagine a world without numbers.It took thousands of years to get the decimal number system.In the stone age man used pebbles sticks & different types of symbols for counting numbers.all the techniques requires some physical power from man.The process was very slow & a lot of works was required for large calculation.Later on above techniques were replaced by the present day number system.Besides decimal number system there are other system namely binary ,octel & hex.

1 ) Decimal number system
The number system having base10 is called decimal number system.it includes 10 digits.Since there are 10 digits in decimal number system it’s base is 10.The order of base values in decimal number system are 1 ,10 ,100 ,1000 e.t.c.

2) Binary number system
The number system having base 2 is called binary number system.It includes only two digits 0 & 1.Since there are omly two digits it’s base value is two.The order of two values in binary number system are 1 ,2 ,4 ,8 ,16 ,32 ,84 ,128 , & so on.
1 or 0 is also called bit ,which represents two logic conditions:
1.True &
2.False

1) Octal number system
The number system having bsae 8 is called octal number system.it includes 8 digits i.e. 0-7.Since there are 8 digits in octal number system it’s base is 8.

5)Hexa decimal number system
The number systemj having base 16 is called hexa decimal number system.It includes 16 digits.eg: (0-9 A ,B ,C ,D ,E ,F).Since there are 16 digits it’s base is 16.