HOW DATA IS STORED IN COMPUTERS?

We should have an idea about the various number systems to understand about how the data is stored in computers.

Numbering System :

The four numbering systems in vogue are:

Numbering System Name Contains Base

Decimal Numbering system 0 to 9 10

Binary Numbering system 0 and 1 2

Octal Numbering system 0 to 7 8

Hexa Decimal Numbering system 0 to 9,A to F 16

The decimal numbering system based on the number 10 is what we are using in our daily life. The binary numbering system contains two elements i.e 0 and 1. In other words a binary number should contain only 0 and 1.

Example: The decimal number 9 is represented as binary number 1001.

To convert the decimal number into binary number , the number should be divided by 2 and the quotient should be further divided by 2until the reminder is equal to 0 or 1.

e.g 2|9

2| 4 -1

2| 2-0

1-0 ie. 1001

The binary number system is ideal for storing the data because of the two state nature of electronic pulses. These pulses represent either circuits are conducting or non conducting; a pulse or voltage is present or not. The binary number system which has only two digits, zero(0) and one(1) is very convenient to express two possible states. The computer arithmetic using binary system is versatile, since by adding two BITS(Binary Digits) the result will also be made up of 1s and 0s. Thus the result is once again represented in a bit pattern of different combinations of pulses and no pulses.

The computer performs all its functions such as subtraction, division and multiplication by a form of addition only. Subtraction is treated as addition of negative numbers. Multiplication is treated as repeated addition and division is repeated subtraction. These are called as complementary additions and complimentary subtractions.

The data storage inside the computer is achieved through ‘Character Sets’. These characters (which we see on the keyboard) are alphanumeric characters, numeric characters, special characters and various control characters.

If we type a character say ‘A ‘ using the key board that character ‘A’ is converted in to ASCII( American Standard Code for Information Interchange) code which is 65. The ASCII code 65 is converted into equivalent binary number i.e 1000001. This binary number is stored in the disk. At the time of retrieval of the value , the computer converts the binary number into ASCII code (65) and gives the equivalent character ‘A’.

A binary digit is called a bit. A byte is the collection of 8 bits.

1 byte = 8 bits

1 Kilo Byte (KB) = 1024 bytes

1 Mega Byte(MB) =1024 Kilo Bytes

1 Giga Bytes(GB) =1024 Mega Bytes

1 Tera Byte(TB) =1024 Giga Bytes

1 Pica Byte(PB )= 1024 Tera Bytes