The PC keyboard with its various keys has a long history of evolution reaching back to
typewriters and
teletypewriters. In addition to the 'old' standard keys, the PC keyboard has accumulated several special keys over the years. Some of the additions have been inspired by the opportunity or requirement for improving user productivity with general office
application software, while other slightly more general keyboard additions have become the factory standards after being introduced by certain
operating system or
GUI software vendors such as
Microsoft.
From typewriters • pushed the carriage one position backwards. In computers with video displays also deletes the character at that position. • produces an ASCII
tab character, moving to the next tab stop. • wraps to the next line or activates the default or selected option. ASCII keyboards were labeled CR or Return. Typewriters used a lever that would return the cylinder with the paper to the start of the line. • selects upper case, or if shift is pressed, lower case of letters. In mechanical typewriters, it worked like the Shift key, but also used a lock to keep the Shift key depressed. The lock was released by pressing the Shift key. • selects the upper character, or upper case of letters. The Shift key in typewriters was attached to a lever that moved the character types so that the uppercase characters could be printed on the paper. • its main purpose is to enter a
space between characters.
From teletypewriter • produces an ASCII
escape character. It may be used to exit menus or modes. • is a
backtick or grave accent, also formerly backspaced over letters to write non-English languages; on some systems it is used as an opening quote. The single quote ' is normally used for an acute accent. • is the
tilde, an accent backspaced and printed over other letters for non-English languages. Nowadays the key does not produce a backspaceable character in US/UK keyboard layouts, and is used for 'not' or 'circa'. • is a
circumflex, another accent for non-English languages. Also used to indicate
exponentiation where
superscript is not available. • is an
asterisk, used to indicate a note, or multiplication. • is an
underscore, which can be backspaced and overprinted to add emphasis, or in certain
Programming Languages in place of a to form a compound word where the use of would yield several separate words. • is a
vertical bar, originally used as a typographic separator for optical character recognition. Many character sets break it in the middle so it cannot be confused with the numeral "1" or the letter "l" (in most
EBCDIC codepages, vertical bar and divided vertical bar are separate characters). This character is often known as a "pipe" (after its use in
Unix shells) or a "fencepost". • shifts the value of letters and numbers from the ASCII graphics range, down into the
ASCII control characters. For example, CTRL-S is XOFF (stops many programs as they print to screen) CTRL-Q is XON (resume printing stopped by CTRL-S).
From computers with video displays •
Function keys, from to , are the F-numbered keys. Their use varies by program; is often Help. • / originally printed a text image of the screen. (On modern computers, usually takes a screenshot.) With the Alt key, it switched to , a different keycode. • is little-used. IBM documentation described it as "inactive", and the key's purpose was a mystery even to keyboard manufacturers. In modern software, typing text usually causes previous text to scroll off the top of the screen or window. Some old programs could disable this and restart at the top of the window when scroll lock was pressed. The advantage is that the entire screenful of text does not shift, making it easier to read. Scroll Lock was also used to lock the cursor on its line and scroll the work area under it. In spreadsheets such as
Microsoft Excel, it locks the cell pointer on the current cell, allowing the user to use the arrow keys to move the view window without moving the cell pointer. On some consoles (such as the
Linux console), it prevents scrolling of messages until another key combination is pressed. Many hardware
KVM switches use Scroll Lock to switch between the devices they control. • / pauses output or processing. In combination with Ctrl, it produces a keycode for . traditionally stopped programs in DOS. is also used to halt execution of the debugger in some programming environments such as Microsoft Visual Studio. In combination with the Windows key, it opens the System Properties window in Microsoft Windows environments. • originally toggled between text insertion and overwrite modes. Importantly, it is involved along with Ctrl and Shift keys in keyboard shortcuts for copy () and paste () according to the
IBM CUA user interface guidelines; the IBM CUA shortcuts are still widely supported by most current PC operating systems, and many PC users who learned those shortcuts between the late 1980s and the early 1990s may still find them more natural, convenient, or ergonomic than their "modern" Ctrl+X/C/V counterparts, given the close proximity of the Ctrl, Shift and Insert keys to the cursor movement keys. This particular role of the Insert key is often overlooked by modern-times documentation, if not hardware design, which tend to attribute to "Insert" only its more obvious, but much less frequently used and somewhat obsolete, original function. • deletes the character after the cursor, or the selected items. • moves the cursor to the start of text, usually the left side of the screen. • moves the cursor to the end of the current line. • and move through the document by pages. •
Arrow keys (, , , ) move the cursor on the screen. When shifted, they select items. • toggles the state of the
numeric keypad. When off, the keypad acts as arrow and navigational keys. When on, it is a 10-key number pad similar to a standard calculator. Preferences vary so much that a favorite default for this key can often be configured in the BIOS. The key continues to exist on keyboards with separate arrow keys to accommodate those who still prefer the toggleable keypad. • shifts the letters and numbers into the range above hex 0x80 where the international characters and special characters exist in the PC's standard character set.
Alt plus a number typed on the numeric keypad produces special characters; see
Windows Alt keycodes. • is often used in combination with other keys to print special characters like the
backslash on non-English keyboards. It can often be emulated by . • may be present on compact keyboards such as those built into laptop computers. When depressed in combination with other keys, it either enables the user to access key functions that do not have dedicated keys on the compact keyboard (such as the numeric keypad simulation block), or it controls hardware functions such as switching between the built-in screen and an external display, changing screen brightness, or changing speaker volume. These secondary meanings are usually indicated with text or symbols of a different color printed on the key, with the 'Fn' key text having that same color. • (sometimes known outside Windows as is a quick way to open the
Start menu in
Microsoft Windows's standard Explorer shell, and can usually be configured to open the main menu in other operating systems. In Microsoft Windows, the Windows key can also be used in combination with other keys to perform desktop-related actions (e.g. to minimize all open windows, then again to restore them). When connected to a
Macintosh computer, the Windows key behaves like the key. • brings up the active application's context menu, in a similar way to right-clicking. • opens
Microsoft Copilot in Windows. It superseded the menu key on January 4, 2024. The key actually enters . • is present on some keyboards. It is usually on the right side of the right Shift key. When depressed in combination with a
function key it sets the key repeat rate. ==Connection==