COMPUTER CODES

Computer understands everything only in binary. Therefore, when we input numbers, alphabets and other special symbols, they must be represented in the binary format. There are three such coding standards. There are BCD, ASCII and EBCDIC.

1.    BCD (Binary Coded Decimal System :

In BCD each digit of a decimal number is independently converted to 4-bit binary number. For example the decimal number 573 would be represented in the 4 bit BCD code as

0 1 0 1        0 1 1 1      0 0 1 1

       5              7       3

BCD Coding system is used to represent only decimal numbers, 4-bits are insufficient to represent the various characters used by computer. Therefore 6-bit BCD Code was developed. In this code two more bits called as ‘zero position’ are added. It is possible to represent 64 code groups i.e., 10 decimal digits, 26 alphabets and 28 special characters using 6 bit code.

2.    ASCII (American Standard Code for Information Interchange :

It is most widely used alphanumeric code for printers, keyboards and terminals which are interface with computer to represent data. This is 7 bit code and also it has

 128 possible code groups i.e., alphabets, numbers, special characters and control character (Enter Key,    Escape Key, Space bar etc.,). A is represented in ASCII as 1000001 whose decimal equivalent is 65.

3.    EBCDIC (Extended Binary Coded Decimal Interchange Code) :

It is also an alphanumeric code used in IBM computers and mainframe applications. It is an 8 bit code representing 256 different code group. A is represented in EBCDIC code as 11000001.

4.    GRAY CODE

The reflected binary code (RBC), also known as reflected binary (RB) or Gray code after Frank Gray, is an ordering of the binary numeral system such that two successive values differ in only one bit (binary digit).

For example, the representation of the decimal value "1" in binary would normally be "001" and "2" would be "010". In Gray code, these values are represented as "001" and "011". That way, incrementing a value from 1 to 2 requires only one bit to change, instead of two.

Gray codes are widely used to prevent spurious output from electromechanical switches and to facilitate error correction in digital communications such as digital terrestrial television and some cable TV systems.

5 UNICODE

Unicode, formally The Unicode Standard, is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, which is maintained by the Unicode Consortium, defines as of the current version (15.0) 149,186 characters covering 161 modern and historic scripts, as well as symbols, emoji (including in colors), and non-visual control and formatting codes.

Unicode's success at unifying character sets has led to its widespread and predominant use in the internationalization and localization of computer software. The standard has been implemented in many recent technologies, including modern operating systems, XML, and most modern programming languages.