Control key
|
|
In computing, a Control key is a key, which when pressed in conjunction with another key, will perform a special operation. The Control key is a modifier key, it is used in the same fashion as the Shift key.
| Contents |
History
On teletypewriters and early computer keyboards, holding down the Control key while pressing another key zeroed the leftmost 3 bits of 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, and while a modern computer can distinguish these two key combinations it usually will not differentate the two.
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.
Notation
There 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 c key:
| ^C | Traditional notation |
| C-c | Emacs notation |
| Ctrl-C | Old Microsoft notation |
| CTRL+C | New Microsoft notation |
Examples
The following examples may differ in some applications, but are nearly universal throughout the Microsoft Windows family of operating systems.
| CTRL+A | "select all" |
| CTRL+C | "copy" |
| CTRL+S | "save" |
| CTRL+X | "cut" |
| CTRL+V | "paste" |
Similar concepts
Generally, the Command key, labeled with the ⌘ symbol on Apple Macintosh computers, performs the equivalent functions in Mac OS applications. (For example, Command+c copies, while Command+p prints; the same holds for saving, cutting, and pasting. Ironically, the use of these standardized keyboard commands across applications originated in the graphical Macintosh, before migrating to other platforms.)
See also
External link
- Control keys for quick using PC (http://www.hassanzadeh.netfirms.com/Teaching.htm)de:Strg