explain

Example 8.3. Even parity, a commonly used coding scheme, is much more efficient than the simple repetition scheme. The ASCII (American Standard Code for Information Interchange) coding system uses binary 8-tuples, yielding 28 = 256 possible 8-tuples. However, only seven bits are needed since there are only 2 128 ASCII characters. What can or should be done with the extra bit? Using the full eight bits, we can detect single transmission errors. For example, the ASCII codes for A, B, and C are A = 65,9 = 01000001,, B = 6649 = 010000102, C = 6719 = 010000119. Notice that the leftmost bit is always set to 0; that is, the 128 ASCII characters have codes 000000005 = 049, 011111119 = 127 0. The bit can be used for error checking on the other seven bits. It is set to either 0 or 1 so that the total number of 1 bits in the representation of a character is even. Using even parity, the codes for A, B, and C now become A = 010000012, B = 010000102, _ qA4anAmMma a