Caps Lock

The caps lock key on a modern keyboard (near upper-left corner, below the Tab key)

Caps lock is a key on many computer keyboards. Pressing it sets an input mode in which typed letters are uppercase by default. The keyboard remains in caps lock mode until the key is pressed again. On some computers, holding down the shift key while caps lock is on temporarily switches to lowercase.

User interfaces

Caps lock on an Apple Wireless keyboard. The green LED on the key is lit, indicating that caps lock is on.

Keyboards often include a small LED to indicate that caps lock is active—either on the key itself, or in a row with scroll lock and num lock indicators. However, some new laptop and wireless desktop keyboards lack the LED, instead providing software that gives an on-screen indicator.

People typing case-sensitive passwords that are not displayed verbatim on the screen may not realize that caps lock is on, causing errors. Help guides, tech support materials, and sometimes the interface itself may include advice on checking caps lock before typing a password. In Windows login screens, a warning that caps lock is on is shown in a balloon near the field. In Mac OS X, when caps lock is on, a caps lock symbol (⇪) is displayed inside a password field. Operating systems may also provide audible notifications when caps-lock, num-lock, or scroll-lock buttons are toggled.

Some manufacturers include an option in the controller software to deactivate the caps lock key. This behaviour allows users to decide themselves whether they want to use the key, or to disable it to prevent accidental activation.

A physically blocked caps lock key

History

The keyboards of many early computer terminals, including the ASR-33 Teletype and Lear-Siegler ADM-3A, and early models of the IBM PC, positioned the Ctrl key where caps lock resides on modern keyboards.

The undesirable attributes of caps lock have led some power users to swap the positions of the two keys using aftermarket modifications; in the same vein, the One Laptop Per Child computers opt to place Ctrl in the caps lock position and discard caps lock entirely. In a similar vein, the Google Cr-48 netbook replaces caps lock with a dedicated "Search" key.

Shift lock

Although a shift lock key is not the same thing as a caps lock key, it is nowadays rare for a computer to have both. For instance, the Commodore 64 had a shift lock but no caps lock: by depressing the key labeled "Shift Lock", it latched and stayed that way until unlatched, and brought up again. With the Commodore 64, there was no scan code associated with the shift lock key because it served only one purpose—grounding all of the keyscan lines as though the shift key were being pressed.

Some operating systems and window managers allow caps lock to be used for a similar function. This behaviour of the caps lock survives, however, in German and Austrian keyboards.

On modern QWERTY keyboards, though the caps lock mode capitalises letters, it does not affect other keys, such as numbers or punctuation, in the way that the shift key does. A version of caps lock that affects all keys as though it were a shift key does exist on certain layouts such as the French AZERTY and those of some older computers. The origin of the function is found on mechanical typewriters, where the shift key causes the entire type apparatus to elevate upwards, physically shifting to produce capitals and secondary characters.

International Caps Lock Day

28 June and 22 October are annually marked as International Caps Lock Days as a parody holiday first noted in 2000 <ref>Blass, Evan (October 22, 2006). "HAPPY INTERNATIONAL CAPS LOCK DAY". The Next Web. Retrieved October 22, 2010.

External links

• Wiki:CapsLockOff—describes how to remap the caps lock key for other purposes.
• CAPSoff Official Website
• Caps lock day official site.

IBM PC keyboard (Windows, ANSI US layout)
Esc		F1	F2	F3	F4		F5	F6	F7	F8		F9	F10	F11	F12		PrtScn/ SysRq	Scroll Lock	Pause/ Break
																	Insert	Home	PgUp		Num Lock	∕	∗	−
																	Delete	End	PgDn		7	8	9	+
																					4	5	6
																		↑			1	2	3	Enter
																	←	↓	→		0    Ins		.  Del