Explanation

A set of codes that extends the basic ASCII set. The basic ASCII set uses 7 bits for each character, giving it a total of 128 unique symbols. ASCII coding provides 128 characters while extended ASCII coding provides 256 characters. ASCII, abbreviation of American Standard Code For Information Interchange, a standard data-transmission code that is used by smaller and less-powerful computers to represent both textual data (letters, numbers, and punctuation marks) and noninput-device commands (control characters). Like other coding systems, it converts information into standardized digital formats that allow computers to communicate with each other and to efficiently process and store data. The ASCII code was originally developed for teletypewriters but eventually found wide application in personal computers. The standard ASCII code uses seven-digit binary numbers; i.e., numbers consisting of various sequences of 0’s and 1’s. The code can represent 128 different characters, since there are 128 different possible combinations of seven 0’s and 1’s. The binary sequence 1010000, for example, represents an uppercase “P,” while the sequence 1110000 represents a lowercase “p.” Digital computers use a binary code that is arranged in groups of eight rather than of seven digits, or bits. Each such eight-digit group is called a byte. Because digital computers use eight-bit bytes, the ASCII code is commonly embedded in an eight-bit field consisting of the seven information bits and a parity bit that is used for error-checking purposes or to represent special symbols. The use of an eight-bit system increased the number of characters the code could represent to 256. The eight-bit system, which is known as the extended ASCII code, was introduced in 1981 by the International Business Machines Corporation (IBM) for use with its first model of personal computer. This extended ASCII code soon became the industry-wide standard for personal computers.