Representation of Data/Information


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Computer does not understand human language. Any data, viz., letters, symbols, pictures, audio, videos, etc., fed to computer should be converted to machine language first. Computers represent data in the following three forms −

Number System

We are introduced to concept of numbers from a very early age. To a computer, everything is a number, i.e., alphabets, pictures, sounds, etc., are numbers. Number system is categorized into four types −

  • Binary number system consists of only two values, either 0 or 1

  • Octal number system represents values in 8 digits.

  • Decimal number system represents values in 10 digits.

  • Hexadecimal number system represents values in 16 digits.

Number System
System Base Digits
Binary 2 0 1
Octal 8 0 1 2 3 4 5 6 7
Decimal 10 0 1 2 3 4 5 6 7 8 9
Hexadecimal 16 0 1 2 3 4 5 6 7 8 9 A B C D E F

Bits and Bytes

Bits − A bit is a smallest possible unit of data that a computer can recognize or use. Computer usually uses bits in groups.

Bytes − group of eight bits is called a byte. Half a byte is called a nibble.

Bits and Bytes

The following table shows conversion of Bits and Bytes −

Byte Value Bit Value
1 Byte 8 Bits
1024 Bytes 1 Kilobyte
1024 Kilobytes 1 Megabyte
1024 Megabytes 1 Gigabyte
1024 Gigabytes 1 Terabyte
1024 Terabytes 1 Petabyte
1024 Petabytes 1 Exabyte
1024 Exabytes 1 Zettabyte
1024 Zettabytes 1 Yottabyte
1024 Yottabytes 1 Brontobyte
1024 Brontobytes 1 Geopbytes

Text Code

Text code is format used commonly to represent alphabets, punctuation marks and other symbols. Four most popular text code systems are −

  • EBCDIC
  • ASCII
  • Extended ASCII
  • Unicode

EBCDIC

Extended Binary Coded Decimal Interchange Code is an 8-bit code that defines 256 symbols. Given below is the EBCDIC Tabular column

EBCDIC

ASCII

American Standard Code for Information Interchange is an 8-bit code that specifies character values from 0 to 127.

ASCII Tabular column

ASCII Code Decimal Value Character
0000 0000 0 Null prompt
0000 0001 1 Start of heading
0000 0010 2 Start of text
0000 0011 3 End of text
0000 0100 4 End of transmit
0000 0101 5 Enquiry
0000 0110 6 Acknowledge
0000 0111 7 Audible bell
0000 1000 8 Backspace
0000 1001 9 Horizontal tab
0000 1010 10 Line Feed

Extended ASCII

Extended American Standard Code for Information Interchange is an 8-bit code that specifies character values from 128 to 255.

Extended ASCII Tabular column

Extended ASCII

Unicode

Unicode Worldwide Character Standard uses 4 to 32 bits to represent letters, numbers and symbol.

Unicode Tabular Column

Unicode

computer_concepts_introduction_to_computer.htm
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