Fn, short for 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 due to their keyboard size
restrictions. It is also found on many full-sized "multimedia" keyboards as the
F-Lock key. It is mainly for the purpose of changing display or audio settings
quickly, such as brightness, contrast, or volume, and is held down in
conjunction with the appropriate key to change the settings.
Compact layouts Typically, in a compact layout the main
area of the keyboard is kept in much the same layout as with a full-sized
keyboard, and the numeric keypad is moved to share a group of central keys.
This allows typists to enter text without having to learn a new layout.
The symbol that is accessed through pressing Fn is often printed on the key
in a smaller font, a box, or different color.
This 78-key UK layout is taken from the Apple iBook. Characters in blue are
accessed through the Fn key, but functions on the top row can be accessed
without Fn key in Mac OS X. Technical details
Fn is a modifier key, and works like other modifiers keys, such as Ctrl,
Shift and AltGr. For a standard modifier key, the microcontroller inside the
keyboard sends a scancode for the modifier itself, which is then
interpreted by the operating system and combined with other simultaneous
key-presses. The Fn key is a form of meta-modifier key, in that it causes the
operating system to see altered scancodes when other keys on the
keyboard are pressed. This allows the keyboard to directly emulate a
full-sized keyboard, so the operating system can use standard keymaps designed
for a full-sized keyboard. However, because the operating system has no
notion of the Fn key, the key can not normally be remapped in software, unlike
all other standard keyboard keys. While it is most common for the Fn key
processing to happen directly in the keyboard micro-controller, offering no
knowledge to the main computer of whether the Fn key was pressed, some
manufacturers, like Lenovo, perform this mapping in BIOS running on the main CPU,
allowing remapping the Fn key by modifying the BIOS interrupt handler;
and Apple, in which the Fn key is mappable and serves other uses too, as
triggering the Dictation function by pressing the Fn key twice.
In addition to being mapped to standard keyboard keys like Scroll Lock and Num
Lock, the Fn key combinations may also be mapped to control system interfaces
to change the LCD brightness, VGA output, or speaker volume on most laptop
computers. Fn and Control key placement
There is not yet an agreed-upon standard for the placement of the Fn key. It is
usually placed adjacent to the left Control key, shrinking and displacing it
in the process. The control key is most frequently associated with handy
modifier keystrokes such as cut-and-paste, or application shortcuts
such as control-s to save. The wide control key on a full size IBM PC
keyboard layout allows users to become accustomed to using either the left or
right side of the key for these shortcuts. In turn, shrinking and
displacing it either to the left or the right causes considerable user-annoyance
for a set of users. Further aggravating the situation is the
fact that the Fn key is a hardware meta-key which is not remappable through
operating system level keyboard remapping tools, However Lenovo ThinkPad
systems do allow remapping in the BIOS. One solution, which side-steps the fn
and control placement issue, is remapping Caps-Lock as Control. This
places Control in an easier to access location to the left of A-key and above
the left-shift-key, a location that is favored by some Vim and Emacs users and
was used on Unix workstations. Most manufacturers today have shrunk and
displaced the control key to the lower-left corner of the keyboard,
placing Fn to its right. This includes most laptops from HP, Dell, Samsung, and
Lenovo Ideapads. Lenovo Thinkpads place the Fn key in the
lower left, displacing control to the right. However, unlike most other
manufacturers, the control key remains an oversize key. Keyboards have been a
strong source of loyalty for the brand due to both feel and layout, especially
among highly technical users, and Thinkpad keyboards are highly regarded
as some of the best laptop keyboards. However, their Fn key placement is
sometimes a sticking point for users of other brands.
Apple Laptops place Fn in the lower-left and shrink control to the right.
However, Apple's OS X is somewhat less sensitive to control key shrinking, as
it uses the Command-key for many common modifiers, making text-copy the PC
keyboard equivalent of Windows-C instead of Ctrl-C.
= Control Key Preference Factors = Paramount seems to be whether the user
keeps their palm stationary on a wrist rest or not. Other factors include the
control key's size, displacement, and position relative to the left-shift key.
A touch typist who prefers to keep their palm resting on a fixed position has
difficulty reaching a lower-left control, whereas they can reach a
right-displaced control without palm movement. Executing a control-and-shift
operation with a right-displaced-control involves curling the little finger
slightly underneath the ring-finger. Control key combinations involving the
upper-left of the keyboard, including the keys require either moving the hand,
or using the right-control key with the opposite hand.
A user who hovers their hands and/or moves them laterally may prefer the
lower-left control, as combined with movement of the palm, it offers a more
open access to the leftmost keys. It also allows control-and-shift operations
to be performed without curling the little finger underneath. Some
workarounds include using little-finger-shift and
ring-finger-control or thumb-control presses. Such change to the point of
origin does reduce the useful radius of the first four fingers across the
keyboard, yet may be more ergonomic for the hand.
On a fullsize keyboard, some users access the lower-left Control key using
the side of their palm, a technique which is not generally possible on
shallow throw laptop keyboards with wrist rests.
References ^ Fn Cntrl Swap Lenovo Laptops
^ Lenovo Fn Key ^ Thinkpad Fn Ctrl Key
^ Lenovo Fn Control Swap ^ FN key placement - I want my control
^ Fn vs Ctrl let the games begin ^ Fn Key Remapping
^ Fn Cntrl Swap Lenovo Laptops ^ Moving the Ctrl Key
^ Thinkpad X1: Designing the Ultimate Keyboard
External links Microsoft Keyboards - F Lock Key
What the F-Key?