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Representation of Data/Information
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.
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
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
Unicode
Unicode Worldwide Character Standard uses 4 to 32 bits to represent letters, numbers and symbol.
Unicode Tabular Column
