A function key is a key on a computer or terminal keyboard 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 (ASCII 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 MacOS system software supported system extensions known generally as FKEYS which could be installed in the System file and could be accessed with a Command-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 Pro Keyboard 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. Current Mac keyboards include specialized function keys for controlling sound volume.
- Apple Macintosh laptops: Function keys were not standard on Apple laptop 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: six unlabelled keys, each with a LED beside it which illuminates when the key can be used; above the keys is a liquid crystal display—the 'microscreen'—that is used by programs to display the action performed by the key.
- Atari 8-bit family (400/800/XL/XE): 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 key. Atari 1200XL had four additional keys labeled F1 through F4 with pre-defined actions, mainly related to cursor movement.
- Atari ST: ten parallelogram-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: 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.
- Commodore VIC-20 and C64: 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: 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 key.
- 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.
- Graphing calculators, particulary those from Texas Instruments, Hewlett-Packard and Casio, 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 series terminals: first known instance—late 1970s—of screen labeled function keys (where keys are placed in proximity or mapped to labels on CRT or LCD screen).
- HP 9830: f1–f8 on two rows of four in upper left with paper template label. Also on HP 2640 terminals. An early use of function keys (1972).
- IBM 3270: early models had 12 function keys in a 3×4 matrix at the right of the keyboard, later 24 in two rows on top of the keyboard.
- IBM PC AT and PS/2 keyboard: 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). 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; PF2, help; PF3, menu; PF4, escape to shell[1]) above the numeric keypad.
Action of function keys on various programs, operating systems
In the Mac OS up to Mac OS 9, the function keys could be configured by the user, with the Function Keys control panel, to start a program or run an AppleScript. Mac OS X assigns default functionality to F9, F10, and F11 (Exposé); F12 (Dashboard); and F14/F15 (decrease/increase contrast). On newer Apple laptops, all the function keys are assigned basic actions such as volume control, brightness control, NumLock (since the laptops lack a keypad), and ejection of disks. Software functions can be used by holding down the Fn key while pressing the appropriate function key, and this scheme can be reversed by changing the Mac OS X system preferences.
Under MS-DOS, individual programs could decide what each function key meant to them, and the command line had its own actions (e.g., F3 copied to the current command prompt words from the previous command). Following the IBM Common User Access guidelines, the F1 key gradually became universally associated with Help in most early Windows programs. To this day, Microsoft Office programs running in Windows list F1 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. F5 is also commonly used as a refresh key in many web browsers and other applications, while F11 activates the full screen/kiosk mode on most browsers. Under the Windows environment, the Alt-F4 key is commonly used to quit or close portions of an application. Other function key assignments common to all Microsoft Office applications are: F7 to check spelling, Alt-F8 to call the macros dialog, Alt-F11 to call the Visual Basic Editor and Shift-Alt-F11 to call the Script Editor. In Microsoft Word, Shift-F1 reveals formatting. In Microsoft PowerPoint, F5 starts the slide show, and F6 moves to the next pane. WordPerfect for DOS is one of the programs that made heavy use of function keys. Function Keys are also heavily used in the BIOS interface. Generally during the power-on self-test, 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, F10 seems to be a fairly wide standard for save and exit which saves all changes and restarts the system.
References
- ^ Ignite-UX Administration Guide: for HP-UX 11.00 and 11i, Appendix D (Terminal Keyboard Shortcuts), Advanced Keyboard Navigation.
| Esc | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F10 | F11 | F12 | PtSc | ScLk | Brk | |||||||||
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rect 0 61 90 90 Tab key rect 90 61 150 90 Q rect 150 61 210 90 W rect 210 61 270 90 E rect 270 61 330 90 R rect 330 61 390 90 T rect 390 61 450 90 Y rect 450 61 510 90 U rect 510 61 570 90 I rect 570 61 630 90 O rect 630 61 690 90 P rect 690 61 750 90 Bracket rect 750 61 810 90 Bracket rect 810 61 900 90 Vertical bar
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rect 0 121 105 150 Caps lock rect 105 121 165 150 A rect 165 121 225 150 S rect 225 121 285 150 D rect 285 121 345 150 F rect 345 121 405 150 G rect 405 121 465 150 H rect 465 121 525 150 J rect 525 121 585 150 K rect 585 121 645 150 L rect 645 121 705 150 Colon (punctuation) rect 705 121 765 150 Quotation mark rect 765 121 900 150 Enter key
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rect 0 181 135 210 Shift key rect 135 181 195 210 Z rect 195 181 255 210 X rect 255 181 315 210 C rect 315 181 375 210 V rect 375 181 435 210 B rect 435 181 495 210 N rect 495 181 555 210 M rect 555 181 615 210 Bracket rect 615 181 675 210 Bracket rect 675 181 735 210 Question mark rect 735 181 900 210 Shift key
rect 0 181 135 240 Shift key rect 135 181 195 240 Z rect 195 181 255 240 X rect 255 181 315 240 C rect 315 181 375 240 V rect 375 181 435 240 B rect 435 181 495 240 N rect 495 181 555 240 M rect 555 181 615 240 Comma (punctuation) rect 615 181 675 240 Full stop rect 675 181 735 240 Slash (punctuation) rect 735 181 900 240 Shift key
rect 0 241 90 300 Control key rect 90 241 150 300 Windows key rect 150 241 240 300 Alt key rect 240 241 600 300 Space bar rect 600 241 690 300 AltGr key rect 690 241 750 300 Windows key rect 750 241 810 300 Menu key rect 810 241 900 300 Control key </imagemap> |
Ins | Home | PgUp | Num | / | * | - | |||||||||||||||||
| Del | End | PgDn | 7 | 8 | 9 | + | ||||||||||||||||||
| 4 | 5 | 6 | ||||||||||||||||||||||
| ↑ | 1 | 2 | 3 | Ent | ||||||||||||||||||||
| ← | ↓ | → | 0 | . | ||||||||||||||||||||
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| Dead keys | Compose |
| Modifier keys | Control · Shift · Alt/Option (Apple) · AltGr · Command/Meta (Apple/MIT/Sun keyboards) · Windows/Super · Fn (compact keyboards) |
| Lock keys | Scroll lock · Num lock · Caps lock |
| Navigation | Arrow · Page Up/Page Down · Home/End |
| Editing | Return/Enter · Backspace · Insert · Delete · Tab · Space bar |
| Misc. | System request/Print screen · Break/Pause · Escape · Menu · Numeric keypad · Function · Power management (Power, Sleep, Wake) · Language input · Any key |
