A
function key is a key on a
computerA computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
or
terminalA computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system...
keyboardIn computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
which can be programmed so as to cause an operating system command interpreter or application program to perform certain actions. On some keyboards/computers, function keys may have default actions, accessible on power-on.
Function keys on a terminal may either generate short fixed sequences of characters, often beginning with the escape character (
ASCIIThe American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
27), or the characters they generate may be configured by sending special character sequences to the terminal. On a standard computer keyboard, the function keys may generate a fixed, single byte code, outside the normal ASCII range, which is translated into some other configurable sequence by the keyboard device driver or interpreted directly by the application program. Function keys may have (abbreviations of) default actions printed on/besides them, or they may have the more common "F-number" designations.
Function key schemes on various computer keyboards
- Apple Macintosh: Early Mac OS supported system extensions known generally as FKEYS which could be installed in the System file and could be accessed with a Command
The Command key, also historically known as the Apple key, open-Apple key or meta key is a modifier key present on Apple Keyboards. The Command key's purpose is to allow the user to enter keyboard shortcut commands to GUI applications...
-Shift-(number) keystroke combination (Command-Shift-3 was the screen capture function included with the system, and was installed as an FKEY); however, early Macintosh keyboards did not support numbered function keys in the normal sense. Since the introduction of the Apple Extended KeyboardThe Apple Extended Keyboard is a keyboard that was first sold separately alongside the Macintosh II and SE.Later the Apple Extended Keyboard II prepackaged with Apple Professional Desktops during the early 1990s...
with the Macintosh II, however, keyboards with function keys have been available, though they did not become standard until the mid-1990s. They have not traditionally been a major part of the Mac user interface, however, and are generally only used on cross-platform programs. According to the Macintosh Human Interface Guidelines, they are reserved for customization by the user. Current Mac keyboards include specialized function keys for controlling sound volume. The most recent Mac keyboards include 19 function keys, but keys F1-F4 and F7-F12 by default control features such as volume, media control, and ExposéExposé is a feature of the Mac OS X operating system. First previewed on 23 June 2003 at the Apple Worldwide Developers Conference as a feature of the then forthcoming Mac OS X v10.3, Exposé allows a user to quickly locate an open window, or to hide all windows and show the desktop without the need...
.
- Apple Macintosh notebooks: Function keys were not standard on Apple notebook hardware until the introduction of the PowerBook 5300 and the PowerBook 190. For the most part, Mac laptops have keys F1 through F12, with pre-defined actions for some, including controlling sound volume and screen brightness.
- Apricot PC/Xi
The Apricot PC was Apricot Computers' first personal computer made for business use. The press received it well, especially for the high resolution of its time and its trackball cable . It is the first non-Japanese computer using 3.5" Sony floppy disc units.It uses a Intel 8086 processor running...
: six unlabelled keys, each with a LEDA light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...
beside it which illuminates when the key can be used; above the keys is a liquid crystal displayA liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....
—the 'microscreen'—that is used by programs to display the action performed by the key.
- Atari 8-bit family (400/800/XL/XE)
The Atari 8-bit family is a series of 8-bit home computers manufactured from 1979 to 1992. All are based on the MOS Technology 6502 CPU and were the first home computers designed with custom coprocessor chips...
: four dedicated keys (Reset, Option, Select, Start) at the right hand side or on the top of the keyboard; the XL models also had a Help keyA Help key, found in the shape of a dedicated key explicitly labeled "Help", or as another key, typically one of the function keys, on a computer keyboard, is a key which, when pressed, produces information on the screen/display to aid the user in his/her current task, such as using a specific...
. Atari 1200XL had four additional keys labeled F1 through F4 with pre-defined actions, mainly related to cursor movement.
- Atari ST
The Atari ST is a home/personal computer that was released by Atari Corporation in 1985 and commercially available from that summer into the early 1990s. The "ST" officially stands for "Sixteen/Thirty-two", which referred to the Motorola 68000's 16-bit external bus and 32-bit internals...
: ten parallelogramIn Euclidean geometry, a parallelogram is a convex quadrilateral with two pairs of parallel sides. The opposite or facing sides of a parallelogram are of equal length and the opposite angles of a parallelogram are of equal measure...
-shaped keys in a horizontal row across the top of the keyboard, inset into the keyboard frame instead of popping up like normal keys.
- BBC Micro
The BBC Microcomputer System, or BBC Micro, was a series of microcomputers and associated peripherals designed and built by Acorn Computers for the BBC Computer Literacy Project, operated by the British Broadcasting Corporation...
: red/orange keys F0 to F9 in a horizontal row above the number keys on top of the computer/keyboard. The break, arrow, and copy keys could function as F10-F15.
- Coleco Adam
The Coleco Adam is a home computer, an attempt in the early 1980s by American toy manufacturer Coleco to follow on the success of its ColecoVision game console...
: six dark brown keys in a horizontal row above the number keys, labeled with Roman numerals I-VI.
- Commodore VIC-20
The VIC-20 is an 8-bit home computer which was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the PET...
and C64The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...
: F1/F2 to F7/F8 in a vertical row of four keys ascending downwards on the computer/keyboard's right hand side, odd-numbered functions accessed unshifted, even-numbered shifted; orange, beige/brown, or grey key color, depending on VIC/64 model/revision.
- Commodore 128
The Commodore 128 home/personal computer was the last 8-bit machine commercially released by Commodore Business Machines...
: essentially same as VIC-20/C64, but with (grey) function keys placed in a horizontal row above the numeric keypad right of the main QWERTY-keyboard; also had Help keyA Help key, found in the shape of a dedicated key explicitly labeled "Help", or as another key, typically one of the function keys, on a computer keyboard, is a key which, when pressed, produces information on the screen/display to aid the user in his/her current task, such as using a specific...
.
- Commodore Amiga: ten keys arranged in a row of two 5-key groups across the top of the keyboard (flush with the ordinary keyboard top row); function keys are 1½ times the width of ordinary keys. Like the Commodore 128, this also had a Help key
A Help key, found in the shape of a dedicated key explicitly labeled "Help", or as another key, typically one of the function keys, on a computer keyboard, is a key which, when pressed, produces information on the screen/display to aid the user in his/her current task, such as using a specific...
.
- Graphing calculator
A graphing calculator typically refers to a class of handheld calculators that are capable of plotting graphs, solving simultaneous equations, and performing numerous other tasks with variables...
s, particularly those from Texas InstrumentsTexas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...
, Hewlett-PackardHewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
and Casiois a multinational electronic devices manufacturing company founded in 1946, with its headquarters in Shibuya, Tokyo, Japan. Casio is best known for its electronic products, such as calculators, audio equipment, PDAs, cameras, musical instruments, and watches...
, usually include a row of function keys with various preassigned functions (on a standard hand-held calculator, these would be the top row of buttons under the screen). On low-end models such as the TI-83-series, these function mainly as an extension of the main keyboard, but on high-end calculators the functions change with the mode, sometimes acting as menu navigation keys as well.
- HP 2640
The HP 2640A and other HP 264X models were block-mode "smart" and intelligent ASCII standard serial terminals produced by Hewlett Packard using the Intel 8008 and 8080 microprocessors.-History:...
series terminals: first known instance—late 1970s—of screen labeled function keysScreen-labeled function keys are a special case of function keys where keys are placed near a screen, which provides labels for them. These are most commonly found in kiosk applications, such as automated teller machines and gas pumps. These were first developed by Hewlett-Packard in the 1970s...
(where keys are placed in proximity or mapped to labels on CRT or LCD screen).
- HP 9830
The HP 9800 was a family of what were initially called programmable calculators and later desktop computers made by Hewlett-Packard, replacing their first HP 9100 calculator...
: f1–f8 on two rows of four in upper left with paper template label. Also on HP 2640The HP 2640A and other HP 264X models were block-mode "smart" and intelligent ASCII standard serial terminals produced by Hewlett Packard using the Intel 8008 and 8080 microprocessors.-History:...
terminals. An early use of function keys (1972).
- IBM 3270
The IBM 3270 is a class of block oriented terminals made by IBM since 1972 normally used to communicate with IBM mainframes. As such, it was the successor to the IBM 2260 display terminal. Due to the text colour on the original models, these terminals are informally known as green screen terminals...
: probably the origin of function keys on keyboards, circa 1972. On this mainframe keyboard early models had 12 function keys in a 3×4 matrix at the right of the keyboard; later that changed to a numeric keypad, and the function keys moved to the top of the keyboard, and increased to 24 keys in two rows.
- IBM 5250
IBM 5250 was originally a family of terminal devices sold with the IBM System/34 minicomputer systems. One model was the IBM 5251-11. It also connected to the later System/36, System/38 and AS/400 systems.- Historical origins :...
: early models frequently had a "cmd" modifier key, by which the numeric row keys emulate function keys; later models have either 12 function keys in groups of 4 (with shifted keys acting as F13-F24), or 24 in two rows. These keys, along with "Enter," "Help," and several others, generate "AID codes," informing the host computer that user-entered data is ready to be read.
- IBM PC AT and PS/2 keyboard
The keyboards for IBM PC compatible computers are standardized. However, during the 3-plus decades of PC architecture being constantly updated, multiple types of keyboard layout variations have been developed....
: F1 to F12 usually in three 4-key groups across the top of the keyboard. The original IBM PC and PC XT keyboards had function keys F1 through F10, in two adjacent vertical rows on the left hand side; F1|F2, F3|F4, ..., F9|F10, ascending downwards. Some IBM compatible keyboards, e.g., the NorthgateNorthgate Computer Systems, Inc., based in Eden Prairie, Minnesota, USA, was a mail-order personal computer company, founded in 1987 by Arthur Lazere....
OmniKey™/102, also featured function keys on the left, which on examples with swapped left Alt and Caps Lock keys, facilitate fingers of a single hand simultaneously striking modifier key(s) and function keys swiftly and comfortably by touch even by those with small hands. Many modern PC keyboards also include specialized keys for multimedia and operating system functions.
- MCK-142 Pro: two sets of F1–F12 function keys, 1 above QWERTY and one to the left. Also, 24 additional user programmable PF keys located above QWERTY keys.
- Sharp MZ-700: blue keys F1 to F5 in a horizontal row across the top left side of the keyboard, the keys are vertically half the size of ordinary keys and twice the width; there's also a dedicated 'slot' for changeable key legend overlays (paper/plastic) above the function key row.
- VT-100 terminals: four function keys (PF1, Alt key
The Alt key on a computer keyboard is used to change the function of other pressed keys. Thus, the Alt key is a modifier key, used in a similar fashion to the Shift key. For example, simply pressing "A" will type the letter a, but if you hold down either Alt key while pressing A, the computer...
; PF2, help; PF3, menu; PF4, escape to shell) above the numeric keypadA numeric keypad, numpad or tenkey for short, is the small, palm-sized, seventeen key section of a computer keyboard, usually on the very far right. The numeric keypad features digits 0 to 9, addition , subtraction , multiplication and division symbols, a decimal point and Num Lock and Enter keys...
.
Action of function keys on various programs, operating systems
In the
Mac OSMac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
up to
Mac OS 9Mac OS 9 is the final major release of Apple's Mac OS before the launch of Mac OS X. Introduced on October 23, 1999, Apple positioned it as "The Best Internet Operating System Ever," highlighting Sherlock 2's Internet search capabilities, integration with Apple's free online services known as...
, the function keys could be configured by the user, with the Function Keys control panel, to start a program or run an
AppleScriptAppleScript is a scripting language created by Apple Inc. and built into Macintosh operating systems since System 7. The term "AppleScript" may refer to the scripting system itself, or to particular scripts that are written in the AppleScript language....
.
Mac OS XMac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
assigns default functionality to , , and (
ExposéExposé is a feature of the Mac OS X operating system. First previewed on 23 June 2003 at the Apple Worldwide Developers Conference as a feature of the then forthcoming Mac OS X v10.3, Exposé allows a user to quickly locate an open window, or to hide all windows and show the desktop without the need...
); (Dashboard); and / (decrease/increase contrast). On newer Apple laptops, all the function keys are assigned basic actions such as volume control, brightness control, (since the laptops lack a keypad), and ejection of disks. Software functions can be used by holding down the
Fn keyFn, or 'Function', is a modifier key on many keyboards, especially on laptops, used in a compact layout to combine keys which are usually kept separate. It is typically found on laptops, since a full-sized keyboard would be difficult to fit in a laptop chassis. It is also found in many full-sized...
while pressing the appropriate function key, and this scheme can be reversed by changing the Mac OS X system preferences.
Under
MS-DOSMS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
, individual programs could decide what each function key meant to them, and the command line had its own actions (e.g., copied to the current command prompt words from the previous command).
Following the IBM Common User Access guidelines, the key gradually became universally associated with Help in most early Windows programs. To this day,
Microsoft OfficeMicrosoft Office is a non-free commercial office suite of inter-related desktop applications, servers and services for the Microsoft Windows and Mac OS X operating systems, introduced by Microsoft in August 1, 1989. Initially a marketing term for a bundled set of applications, the first version of...
programs running in Windows list as the key for Help in the Help menu. Internet Explorer in Windows does not list this keystroke in the help menu, but still responds with a help window. is commonly used to activate a search function in applications, often cycling through results on successive presses of the key. + is often used to search backwards. Some applications such as
Visual StudioMicrosoft Visual Studio is an integrated development environment from Microsoft. It is used to develop console and graphical user interface applications along with Windows Forms applications, web sites, web applications, and web services in both native code together with managed code for all...
support + as a means of searching for the currently highlighted text elsewhere in a document. is also commonly used as a refresh key in many
web browserA web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content...
s and other applications, while activates the
full screenA fullscreen image or video occupies the screen entirely.* A video display having an aspect ratio of 4:3 * In film, the use of pan and scan, image cropping, or windowboxing to fit widescreen content into a display with aspect ratio of 4:3...
/
kiosk modeKiosk software is the system and user interface software designed for a kiosk or Internet kiosk. Kiosk software locks down the application in order to protect the kiosk from users. Kiosk software may offer remote monitoring to manage multiple kiosks from another location...
on most browsers. Under the Windows environment, + is commonly used to quit an application; + will often close a portion of the application, such as a document or tab. generally activates the
menu barA menu bar is a region of a screen or application interface where drop down menus are displayed. The menu bar's purpose is to supply a common housing for window- or application-specific menus which provide access to such functions as opening files, interacting with an application, or displaying...
, while + activates a
context menuA context menu is a menu in a graphical user interface that appears upon user interaction, such as a right mouse click or middle click mouse operation...
. is used in Windows Explorer, Visual Studio and other programs to rename files or other items.
is used in some applications to make the window "fullscreen", like in 3D Pinball: Space Cadet. In Microsoft IE, it is used to view the URL list of previously viewed websites.
Other function key assignments common to all Microsoft Office applications are: to check spelling, + to call the macros dialog, + to call the Visual Basic Editor and ++ to call the Script Editor. In Microsoft Word, + reveals formatting. In Microsoft PowerPoint, starts the slide show, and moves to the next pane.
WordPerfect for DOS is an example of a program that made heavy use of function keys.
Function Keys are also heavily used in the
BIOSIn IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....
interface. Generally during the
power-on self-testPower-On Self-Test refers to routines run immediately after power is applied, by nearly all electronic devices. Perhaps the most widely-known usage pertains to computing devices...
, BIOS access can be gained by hitting either a function key or the delete key. In the BIOS keys can have different purposes depending on the BIOS. However, is the
de facto standardA de facto standard is a custom, convention, product, or system that has achieved a dominant position by public acceptance or market forces...
for save and exit which saves all changes and restarts the system.
During Microsoft Windows startup, is used to enter
safe modeSafe mode is a diagnostic mode of a computer operating system . It can also refer to a mode of operation by application software. Safe mode is intended to fix most, if not all problems within an operating system...
.
In
Internet Explorer 6Internet Explorer 6 is the sixth major revision of Internet Explorer, a web browser developed by Microsoft for Windows operating systems...
and
Internet Explorer 7Windows Internet Explorer 7 is a web browser released by Microsoft in October 2006. Internet Explorer 7 is part of a long line of versions of Internet Explorer and was the first major update to the browser in more than 5 years...
, opens Internet Explorer Developer Toolbar.