Scroll lock

"Scroll lock" is a key (often with an associated status light) on most modern computer keyboards. The behavior of the key depends on the particular software in use.

The scroll lock key is a remnant from the original IBM PC keyboard. In the original design, scroll lock was intended to modify the behavior of the arrow keys. When the scroll lock mode was on, the arrow keys would scroll the contents of a text window instead of moving the cursor. In this usage, scroll lock is a modifier key like Alt and Shift (which modify the function of other keys) and, more specifically, a toggling lock key like Num Lock or Caps Lock, which have a state that persists after the key is released. Today, this particular use of scroll lock is rare. Only a few modern programs still honor this behavior, such as Microsoft Excel (in the behavior of arrows — when scroll lock is on, the selection does not move), Lotus Notes and Forté Agent. In modern GUI environments, scrolling is usually accomplished using means such as scrollbars or scroll wheels. Therefore scroll lock can be regarded as a defunct feature in almost all modern programs and operating systems; some keyboards lack scroll lock altogether.

Scroll lock has fallen into such extremely infrequent use that some of the lighter-weight Linux desktop environments, such as Xfce, don't support it at all.

Other uses

*In Linux virtual consoles, the scroll lock key is used to pause screen output. This behaviour emulates the Hold Screen key or similar flow control mechanisms on computer terminals. Because of this emulation, the term "scroll lock" is sometimes used to generically refer to a screen pausing behaviour. This usage could potentially cause confusion since screen pausing behaviour is not intrinsically a part of the scroll lock key. In DOS, the Pause key pauses the screen output.

*In the Opera web browser the scroll lock key plays an important role in voice recognition.

*KVM switches often use the scroll lock key with a number as a hot key to activate a softswitch for changing between channels. Similarly, the KVM-like software solution Synergy uses scroll lock to keep the keyboard and mouse control within the current screen. Certain 2-computer KVM switches provide that a "double click" of the scroll lock key (striking the key twice quickly) is used to switch between computers.

*In the multilingual text editor iLeap, scroll lock key is used as a toggle switch to change between two languages.

*In Windows NT-based operating systems with a certain registry setting called "CrashOnCtrlScroll" enabled, double tapping scroll lock while holding Ctrl key initiates a system crash to allow debugging the current state of the operating system. [ [http://www.microsoft.com/technet/archive/community/columns/tips/da1100.mspx?mfr=true Microsoft Corporation ] ] [ [http://support.microsoft.com/kb/244139 Windows feature lets you generate a memory dump file by using the keyboard ] ]

*In FreeBSD, and other BSD descendants, Scroll Lock still functions similarly to IBM's original design.

*Apple Keyboards do not have a scroll lock key, except for some ADB keyboards.

*On some Dell laptops the scroll lock key becomes the Fn key when an external keyboard is used. The original behavior can be enabled in the BIOS.

*Individual applications may assign any function to this key as an added convenience hotkey.

*Xfire, a chat application for use while playing a video game, is activated by using the default key combination of "scroll lock" + "X". Xfire also uses Scroll lock for other in-game purposes, such as taking screenshots. Sometimes its LED is used to notify users that an event occurred.

*FL Studio uses scroll lock key to turn on/off cursor autoscrolling during playback.

*In the media system My Media System, navigation is done in a fashion very similar to the original idea of the scroll lock key. At the beginning and end of a list, navigating will move the cursor but not the view. At the middle of the list, the cursor will be locked at the middle of the screen while the view moves.

ee also

*SysRq

References

External links

* [http://www.straightdope.com/mailbag/mscrolllock.html Straightdope article about the scroll lock key]