• In computing, a single character such as a letter, a number or a symbol is represented by a group of bits. The number of bits per character depends on the coding scheme used.
• The most common coding schemes are:
• Binary Coded Decimal (BCD),
• Extended Binary Coded Decimal Interchange Code (EBCDIC) and
• American Standard Code for Information Interchange (ASCII).

Binary Coded Decimal

• Binary Coded Decimal is a 4-bit code used to represent numeric data only. For example, a number like 9 can be represented using Binary Coded Decimal as 1001₂ .
• Binary Coded Decimal is mostly used in simple electronic devices like calculators and microwaves. This is because it makes it easier to process and display individual numbers on their Liquid Crystal Display (LCD) screens.
• A standard Binary Coded Decimal, an enhanced format of Binary Coded Decimal, is a 6-bit representation scheme which can represent non-numeric characters. This allows 64 characters to be represented. For letter A can be represented as 110001₂ using standard Binary Coded Decimal

Extended Binary Coded Decimal Interchange code (EBCDIC)

• Extended Binary Coded Decimal Interchange code (EBCDIC) is an 8-bit character-coding scheme used primarily on IBM computers. A total of 256 (2⁸) characters can be coded using this scheme. For example, the symbolic representation of letter A using Extended Binary Coded Decimal Interchange code is 11000001₂.

American standard code for information interchange (ASCII)

• American standard code for information interchange (ASCII) is a 7-bit code, which means that only 128 characters i.e. 2⁷ can be represented. However, manufactures have added an eight bit to this coding scheme, which can now provide for 256 characters.
• This 8-bit coding scheme is referred to as an 8-bit American standard code for information interchange. The symbolic representation of letter A using this scheme is 1000001₂..