BCD, ASCII and EBCDIC CODES

BCD stands for Binary Coded Decimal. This code is useful for the conversion of numbers into binary form. BCD numbers are binary-coded decimal numbers. In BCD, each decimal digit is represented by its equivalent four-bit binary number. The circuits of pocket calculators can process BCD numbers because you enter decimal numbers through the keyboard and see decimal answers on an LED. Digital clocks, digital voltmeters, and electronic counters work with BCD numbers.

Advantages of BCD 
1. The length of the number is short. 
2. Easy to convert to and from BCD 
3. Suitable for hexadecimal addition.

Example: 1) 100100111001_BCD  

                       =    1001      0011      1001

                                ↓            ↓           ↓

                      =        9            3           9

There are some other codes, like 5421 BCD, 5311 BCD, etc. But the most common method is 8421 BCD.

These codes are normally used for computer keyboards; ASCII code uses either 7-bit code or 8-bit code to represent the numbers and the characters. ASCII stands for American Standard Code for Information Interchange. EBCDIC code is a similar 8-bit code that was developed by IBM, which is obtained by extending a six-bit BCD code. It is an Extended BCD Interchange Code, e.g. In ASCII, the code for CAT is easily obtained by writing the binary code for C, Aand T 
C = 11 0011
A = 11 0001
T = 01 0011 (Refer to the ASCII 7-bit Chart)
CAT = (11 0001    11  0001   01   0011)

ASCII code