Control Characters
A control character is a character that, in isolation, has some control function, such as carriage return (CR). Escape sequences, by contrast, consist of an escape character or sequence which changes the interpretation of following characters.
A common use of escape sequences is in fact to remove control characters found in a binary data stream so that they will not cause their control function by mistake. In this case, the control character is replaced by a defined "escape character" (which need not be the US-ASCII Escape Character) and another character; after exiting the context where the control character would have caused an action, the sequence is recognized and replaced by the removed character. To transmit the "escape character" itself, two copies are sent.
The earlier VT52 terminal used simple digraph commands like escape-A: in isolation, "A" simply meant the letter "A", but as part of the escape sequence "escape-A", it had a different meaning. The VT52 also supported parameters: it was not a straightforward control language encoded as substitution.
Read more about this topic: Escape Sequence
Famous quotes containing the words control and/or characters:
“If someone does something we disapprove of, we regard him as bad if we believe we can deter him from persisting in his conduct, but we regard him as mad if we believe we cannot. In either case, the crucial issue is our control of the other: the more we lose control over him, and the more he assumes control over himself, the more, in case of conflict, we are likely to consider him mad rather than just bad.”
—Thomas Szasz (b. 1920)
“Philosophy is written in this grand book—I mean the universe—
which stands continually open to our gaze, but it cannot be understood unless one first learns to comprehend the language and interpret the characters in which it is written. It is written in the language of mathematics, and its characters are triangles, circles, and other geometrical figures, without which it is humanly impossible to understand a single word of it.”
—Galileo Galilei (1564–1642)