by Dinesh Thakur

Earlier computers were used only for the purpose of calculations i.e. they were only used as a calculating device. But now computers are not just used for numeric representations, they are also used to represent information such as names, addresses, item descriptions etc. Such information is represented using letters and symbols. Computer is a digital system and can only deal with l's and 0’s. So to deal with letters and symbols they use alphanumeric codes.



 
by Dinesh Thakur

The Gray code was designed by Frank Gray at Bell Labs in 1953. It belongs to a class of codes called the minimum change code. The successive coded characters never differ in more than one-bit. Owing to this feature, the maximum error that can creep into a system using the binary gray code to encode data is much less than the worst -case error encountered in case of straight binary encoding.

 
by Dinesh Thakur

Excess-3, also called XS3, is a non-weighted code used to express decimal number-s. It is another important binary code. It is particularly significant for arithmetic operations as it overcomes the shortcomings encountered while using the 8421 BCD code to add two decimal digits whose sum exceeds 9. This code is used in some old computers.



 
by Dinesh Thakur

The binary coded decimal (BCD) is a type of binary code used to represent a given decimal number in an equivalent binary form. Its main advantage is that it allows easy conversion to decimal digits for printing or display and faster calculations.

 
by Dinesh Thakur

Digital data is represented, stored and transmitted as groups of binary digits also known as binary code. The binary codes can be classified as shown in Fig.