Editing Shift lock

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[[File:SHIFT_LOCK_001.jpg|right|200px|thumb|Shift lock key]]

'''Shift lock''' is a [[lock key]] on early computer keyboards which had the effect of locking down shift. Unlike [[caps lock]], all keys are [[shift key|shift]]ed. If the keyboard does not support reversing the effects of shift lock (by holding shift while shift lock is engaged), it becomes impossible to type digits in most layouts unless there is a dedicated [[numeric keypad]]. One exception is the [[AZERTY]] layout, which requires shift to type numbers in the first place.

[[Caps lock]] allows the operator to enter capitalised text without affecting the ability to type digits or symbols, making it arguably more practical than shift lock; shift lock mirrors the behaviour of typewriters where the shift key physically moved the typebar array.

The Acorn BBC Microcomputer and later Master Series Microcomputer featured both caps lock ''and'' shift lock. When caps lock is enabled (boot-time default), lowercase cannot be entered. By typing shift+caps lock, the OS enters inverted caps lock mode, where holding shift does provide lowercase, the same as how PCs operate. This behaviour does not extend to shift-lock mode.

===Mechanical shift lock===
A mechanical shift lock is a mechanism that allows the shift lock function to be released by pressing the shift key. Mechanical linkages connect the shift keys on either side of the keyboard into the shift lock key; pressing either shift key will mechanically release the shift key. Although this is seldom confirmed, the implication is that the shift lock key itself must be [[alternate action]].

Originally a mechanical typewriter function, this functionality was included in several keyboard switch types. This functionality is typically found in electric typewriters, but the [[Xerox X998]] computer keyboard also features a mechanical shift lock.<ref name="X998" />

In most cases, no catalogues have been found for the switch types in question, so we do not know if these were ad-hoc products or off-the-shelf designs. However, the mechanical shift lock feature of [[Cherry gold crosspoint]] is included in [[Cherry catalogues]] as a standard option.

==Switch types==
See [[:Category:Mechanical shift lock switches|Mechanical shift lock switches]]

==References==
<references>
<ref name="X998">Deskthority — [https://deskthority.net/photos-f62/xerox-x998-t12336.html Xerox X998]</ref>
</references>

[[Category:Keyboard terms]]

[[Category:Lock keys]]