1. Lecture Coding Schemes

2. Representing Data English language uses 26 symbols to represent an idea Different sets of bit patterns have been designed to represent text symbols Each set is called a code

3. Common Codes ASCII Extended ASCII EBCDIC Unicode

4. ASCII The American National Standards Institute (ANSI) developed a code called ASCII (American Standard Code for Information Interchange) This code uses 7 bits for each symbol 2 7 = 128 different symbols can be defined by the code

5. Figure 2-5 Representation of the word “BYTE” in ASCII code

7. Extended ASCII ASCII bit pattern augmented with an extra 0 on the left to represent it in a byte Some manufacturers used it to create an extra 128 symbols however, this attempt has not been very successful

8. EBCDIC IBM developed a code called EBCDIC – Extended Binary Coded Decimal Interchange Code It uses 8-bit patterns – It can represent up to 256 symbols This code is not used in any computers other than IBM

9. Unicode To represent symbols belonging to other languages a code with greater capacity was needed Unicode uses 16 bits and can represent up to 2 16 = 65,536 symbols defines codes for characters used in all the major languages written today