Computer keyboards evolved from the IBM electric typewriter keyboards that were the basis of the 83-key keyboard for the original IBM PC. With the second-generation AT PC, IBM introduced a 101-key version similar to modern keyboards. This keyboard moved the function keys to the top and the numeric keypad to the right. Since then, Windows function keys and a few additional control keys, depending on the keyboard, have raised the total to about 105 keys but left the basic layout the same.
The alphanumeric part of the keyboard shows the letters, numbers, punctuation and a few symbols such as percent and dollar sign. The standard U.S. keyboard shows only Western, English characters, but the ASCII Code that is the basis for keyboards can type 256 characters, including accented and special characters from European languages. You can type these on your U.S. keyboard by holding down the "Alt" key and typing the ASCII number of the character, available from an ASCII reference such as "The ASCII Code." You can type all 256 characters this way.
You can find the twelve function keys across the top of the keyboard. The functions they carry out depend mainly on the computer and software that you are using, but there are some standard functions. "F1" usually opens a help file. "F2" lets you edit a selection, for example a cell in MS Excel. "F3" opens "Find." "F4" repeats an action such as bolding text. "F5" gives a refresh command. The other keys often have specific functions, depending on the program that is open. Some computers also use them to control screen brightness and sound volume.
The two control keys, "Ctrl" and "Alt," are at the bottom left and bottom right of the alphanumeric part of the keyboard. They are designed to be held down in conjunction with other keys to accomplish specific functions. Particularly useful is "Ctrl" plus "C" to copy a selected text to the clipboard and "Ctrl" plus "V" to paste it. "Ctrl" plus "B," "I," or "U" bolds, italicizes or underlines selected text. "Alt" plus "F4" closes the current program window. "Alt" plus underlined letters in Windows menus carries out the corresponding functions.
The navigation keys are the arrow keys and others to the left of the numeric keypad. They work as expected except for the "Insert" key which toggles between insert and overwrite in word processors. If your word processor suddenly starts overwriting text when you want to insert it, press the "Insert" key to toggle back. Above the navigation keys are legacy keys that are rarely used. "Print Screen" copies an image of the screen to the clipboard from where you can paste it into a graphics program like Paint to obtain a screen capture image.
The numeric keypad to the right of the keyboard allows you to enter numbers quickly with one hand. Basic arithmetic functions are there as well. The "Num Lock" function must be selected, as usually indicated by a "Num Lock" LED that lights up. If "NUM Lock" is not selected, the numeric keypad acts as a duplicate to the navigation keys, rather than outputting numbers. The numeric keypad works with the Windows calculator, found in the Start menu under Accessories. It displays a calculator on the screen with numeric keys in the same arrangement as the keypad.
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