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"Ctrl" redirects here. For the railway line, see High Speed 1. For a list of keyboard shortcuts, see Table of keyboard shortcuts.
In computing, a Control key is a modifier key which, when pressed in conjunction with another key, will perform a special operation (for example, Control-Alt-Delete); similar to the Shift key, the Control key rarely performs any function when pressed by itself. The control key is located on or near the bottom left side of most keyboards. It is usually labeled Ctrl, but sometimes Control or Ctl is seen, and it can be graphically represented as an “up arrowhead” (U+2303, ⌃), or simulated with a caret (^).
[edit] History
On teletypewriters and early keyboards, holding down the Control key while pressing another key zeroed the leftmost 2 bits of the 7 bits in the generated ASCII character. This allowed the operator to produce the first 32 characters in the ASCII table. These are non-printing characters that signal the computer to control where the next character will be placed on the display device, eject a printed page or erase the screen, ring the terminal bell, or some other operation. Aptly, these characters are also called control characters. Note that using the Control key with either lowercase c or uppercase C will generate the same ASCII code on a teletypewriter because holding down the control key grounds (zeros the voltage on) the 2 wires used to carry the leftmost 2 bits from the keyboard. In modern computers the interpretation of keypresses is generally left to the software, modern keyboards distinguish each physical key from every other and report all keypresses and releases to the controlling software. This additional flexibility is not often taken advantage of and it usually does not matter, for example, whether the control key is pressed in conjunction with an upper or a lower case character. When the original purpose of the ASCII control characters became either obsolete or seldom used, later software appropriated the Control key combinations for other purposes. Because on older keyboards the Control key was located on the left of the keyboard, some people remap the keys to exchange Control and Caps Lock, finding the traditional location more ergonomic. [edit] NotationThere are several common notations for pressing the Control key in conjunction with another key. Each notation below means press and hold Control while pressing the x key:
[edit] ExamplesDifferent application programs, user interfaces, and operating systems use the various control key combinations for different purposes.
[edit] Similar conceptsGenerally, the Command key, labeled with the ⌘ symbol on Apple Macintosh computers, performs the equivalent functions in Mac OS X and Mac OS applications (for example, ⌘C copies, while ⌘P prints; the same holds for saving, cutting, and pasting). Macintoshes also have a Control key, but it has different functionality.
[edit] See also[edit] External links
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