Jump to content

Break key: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous edit
Content deleted Content added
VisualWikitext
Tags: Mobile edit Mobile web edit
m Too much "clarification needed" by the way.
 
(41 intermediate revisions by 33 users not shown)
Line 1: Line 1:
{{short description|Key of a computer keyboard}}
{{Redirect|Pause button|the media control|Media controls|other uses|Pause (disambiguation){{!}}Pause}}
{{Redirect|Pause button|the media control|Media controls|other uses|Pause (disambiguation){{!}}Pause}}
[[File:Key break.jpg|right|100px|thumb|Break/Pause key on PC keyboard]]
[[File:Key break.jpg|right|100px|thumb|Break/Pause key on PC keyboard]]
The '''Break key''' of a [[computer keyboard]] refers to breaking a [[Telegraphy|telegraph]] circuit and originated with 19th century practice. In modern usage, the key has no well-defined purpose, but while this is the case, it can be used by software for miscellaneous tasks, such as to switch between multiple login sessions, to terminate a program, or to interrupt a modem connection.
The '''Break key''' (or the symbol <big>'''⎉'''</big>) of a [[computer keyboard]] refers to breaking a [[Telegraphy|telegraph]] circuit and originated with 19th century practice. In modern usage, the key has no well-defined purpose, but while this is the case, it can be used by software for miscellaneous tasks, such as to switch between multiple login sessions, to terminate a program, or to interrupt a modem connection.


Because the break function is usually combined with the pause function on one key since the introduction of the [[IBM Model M]] 101-key keyboard in 1985, the Break key is also called the '''Pause key'''. It can be used to pause some [[computer game]]s.
Because the break function is usually combined with the pause function on one key since the introduction of the [[IBM Model M]] 101-key keyboard in 1985, the Break key is also called the '''Pause key'''. It can be used to pause some [[computer game]]s.


==History==
==History==
A standard telegraph circuit connects all the keys, [[Telegraph sounder|sounders]] and batteries in a single series loop. Thus the sounders actuate only when both keys are down (closed, also known as "marking" &mdash; after the ink marks made on paper tape by early printing telegraphs). So the receiving operator has to hold their key down or close a built-in shorting switch in order to let the other operator send. As a consequence, the receiving operator could interrupt the sending operator by opening their key, breaking the circuit and forcing it into a "spacing" condition. Both sounders stop responding to the sender's keying, alerting the sender. (A physical break in the telegraph line would have the same effect.)
A standard telegraph circuit connects all the keys, [[Telegraph sounder|sounders]] and batteries in a single series loop. Thus the sounders actuate only when both keys are down (closed, also known as "[[mark and space|marking]]" &mdash; after the ink marks made on paper tape by early printing telegraphs). So the receiving operator has to hold their key down or close a built-in shorting switch in order to let the other operator send. As a consequence, the receiving operator could interrupt the sending operator by opening their key, breaking the circuit and forcing it into a "[[mark and space|spacing]]" condition. Both sounders stop responding to the sender's keying, alerting the sender (a physical break in the telegraph line would have the same effect).


The [[teleprinter]] operated in a very similar fashion except that the sending station kept the loop closed (logic 1, or "marking") even during short pauses between characters. Holding down a special "break" key opened the loop, forcing it into a continuous logic 0, or "spacing", condition. When this occurred, the teleprinter mechanisms continually actuated without printing anything, as the all-0s character is the non-printing ''NUL'' in both [[Baudot code|Baudot]] and [[ASCII]]. The resulting noise got the sending operator's attention.
The [[teleprinter]] operated in a very similar fashion except that the sending station kept the loop closed (logic 1, or "marking") even during short pauses between characters. Holding down a special "break" key opened the loop, forcing it into a continuous logic 0, or "spacing", condition. When this occurred, the teleprinter mechanisms continually actuated without printing anything, as the all-0s character is the non-printing ''NUL'' in both [[Baudot code|Baudot]] and [[ASCII]]. The resulting noise got the sending operator's attention.
Line 13: Line 14:


==Sinclair==
==Sinclair==
On the [[Sinclair ZX80]] and [[Sinclair ZX81|ZX81]] computers, the Break is accessed by pressing Space. On the [[Sinclair ZX Spectrum]] it is accessed by {{keypress|Caps Shift|Space}}. The Spectrum+ and later computers have a dedicated {{keypress|Break}} key. It does not trigger an interrupt but will halt any running BASIC program, or terminate the loading or saving of data to cassette tape. An interrupted BASIC program can usually be resumed with the <code>CONTINUE</code> command. The [[Sinclair QL]] computer, without a {{keypress|Break}} key, maps the function to {{keypress|Ctrl|Space}}.
On the [[ZX80]] and [[ZX81]] computers, the Break is accessed by pressing {{keypress|Space}}. On the [[ZX Spectrum]] it is accessed by {{keypress|Caps Shift|Space}}. The Spectrum+ and later computers have a dedicated {{keypress|Break}} key. It does not trigger an interrupt but will halt any running BASIC program, or terminate the loading or saving of data to cassette tape. An interrupted BASIC program can usually be resumed with the <code>CONTINUE</code> command. The [[Sinclair QL]] computer, without a {{keypress|Break}} key, maps the function to {{keypress|Ctrl|Space}}.


==BBC Micro==
==BBC Micro==
Line 21: Line 22:


==Modern keyboards==
==Modern keyboards==
On many modern [[personal computer|PCs]], {{keypress|Pause}} interrupts screen output by [[BIOS]] until another key is pressed. This is effective during [[booting|boot]] in [[text mode]] and in a [[DOS]] box in [[Microsoft Windows|Windows]] safe mode with 50 lines. On early keyboards without a {{keypress|Pause}} key (before the introduction of 101/102-key keyboards) the Pause function was assigned to {{keypress|Ctrl|NumLock}}, and the Break function to {{keypress|Ctrl|ScrLock}}; these key-combinations still work with most programs, even on modern PCs with modern keyboards. Pressing the dedicated {{keypress|Pause}} key on 101/102-key keyboards sends the same [[scancode]]s as pressing {{keypress|Ctrl}}, then {{keypress|NumLock}}, then releasing them in the reverse order would do; additionally, an E1<sub>hex</sub> prefix is sent, which enables 101/102-key-aware software to discern the two situations, while older software usually just ignores the prefix. The {{keypress|Pause}} key is different from all other keys in that it sends no scancodes at all on release; therefore it is not possible for any software to determine whether this key is being held down.<ref>{{cite book|title=PS/2 Hardware Interface Technical Reference|date=October 1990|publisher=IBM|url=http://www.mcamafia.de/pdf/ibm_hitrc11.pdf|page=19|chapter=Keyboard 101- and 102-Key|quote=Except for the Pause key, all keys are make/break.}}</ref>
On many modern [[personal computer|PCs]], {{keypress|Pause}} interrupts screen output by [[BIOS]] until another key is pressed. This is effective during [[booting|boot]] in [[text mode]] and in a [[DOS]] box in [[Microsoft Windows|Windows]] safe mode with 50 lines. On early keyboards without a {{keypress|Pause}} key (before the introduction of 101/102-key keyboards) the Pause function was assigned to {{keypress|Ctrl|NumLock}}, and the Break function to {{keypress|Ctrl|ScrLock}}; these key-combinations still work with most programs, even on modern PCs with modern keyboards. Pressing the dedicated {{keypress|Pause}} key on 101/102-key keyboards sends the same [[scancode]]s as pressing {{keypress|Ctrl}}, then {{keypress|NumLock}}, then releasing them in the reverse order would do; additionally, an E1<sub>hex</sub> prefix is sent, which enables 101/102-key-aware software to discern the two situations, while older software usually just ignores the prefix. The {{keypress|Pause}} key is different from all other keys in that it sends no scancodes at all on release in PS/2 modes 1 or 2, so it is impossible to determine whether this key is being held down with older devices. In PS/2 mode 3 or USB HID mode, there is a release scancode, so it is possible to determine whether this key is being held down on modern computers.<ref>{{cite book|title=PS/2 Hardware Interface Technical Reference|date=October 1990|publisher=IBM|url=http://www.mcamafia.de/pdf/ibm_hitrc11.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.mcamafia.de/pdf/ibm_hitrc11.pdf |archive-date=2022-10-09 |url-status=live|page=19|chapter=Keyboard 101- and 102-Key|quote=Except for the Pause key, all keys are make/break.}}</ref>


On modern keyboards, the {{keypress|Break}} key is usually labeled ''Pause'' with ''Break'' below, sometimes separated by a line: {{Sfrac|Pause|Break}}, or ''Pause'' on the top of the keycap and ''Break'' on the front. In most Windows environments, the key combination {{keypress|Win|Pause}} brings up the system properties.
On modern keyboards, the {{keypress|Break}} key is usually labeled ''Pause'' with ''Break'' below, sometimes separated by a line: {{keypress|{{Sfrac|Pause|Break}}}}, or ''Pause'' on the top of the keycap and ''Break'' on the front, or only ''Pause'' without ''Break'' at all. In most Windows environments, the key combination {{keypress|Win|Pause}} brings up the system properties.


==Keyboards without Break key==
==Keyboards without Break key==
Compact and notebook keyboards often do not have a dedicated {{keypress|Pause/Break}} key.
Compact and notebook keyboards often do not have a dedicated {{keypress|Pause/Break}} key.


These may use the following substitutes for {{keypress|Break}}:
Substitutes for {{keypress|Break}}:
* {{keypress|Ctrl|Fn|F11}} or {{keypress|Fn|B}} or {{keypress|Fn|Ctrl|B}} on certain [[Lenovo]] laptops.<ref>https://support.lenovo.com/us/en/documents/ht074004</ref><ref>http://forum.thinkpads.com/viewtopic.php?f=60&t=98708</ref><ref name="thinkpads1">http://forum.thinkpads.com/viewtopic.php?t=105807</ref>
* {{keypress|Ctrl|Fn|F11}} or {{keypress|Fn|B}} or {{keypress|Fn|Ctrl|B}} on certain{{Clarify|date=August 2023}} [[Lenovo]] laptops.<ref>{{cite web| url = https://support.lenovo.com/us/en/documents/ht074004| title = Keyboard shortcut for Break, Pause, ScrLK, SysRq function on ThinkPad 6 rows Precision keyboard - ThinkPad - Lenovo Support US}}</ref><ref>{{cite web| url = http://forum.thinkpads.com/viewtopic.php?f=60&t=98708| title = Ctrl-Break key - Thinkpads Forum}}</ref><ref name="thinkpads1">{{cite web| url = http://forum.thinkpads.com/viewtopic.php?t=105807| title = T530 Pause/Break key - Thinkpads Forum}}</ref>
* {{keypress|Ctrl|Fn|B}} or {{keypress|Fn|B}} on certain Dell laptops.<ref name=dell>{{Cite web|url=http://cdn.cnetcontent.com/0b/87/0b875d86-4bdc-4b39-a6a0-fe922d9b71a1.pdf#page=18|title=Dell Inspiron 17 specification|last=|first=|date=|website=|publisher=|access-date=}}</ref>
* {{keypress|Ctrl|Fn|B}} or {{keypress|Fn|B}} on certain{{Clarify|date=August 2023}} Dell laptops.<ref name=dell>{{Cite web|url=http://cdn.cnetcontent.com/0b/87/0b875d86-4bdc-4b39-a6a0-fe922d9b71a1.pdf#page=18 |archive-url=https://ghostarchive.org/archive/20221009/http://cdn.cnetcontent.com/0b/87/0b875d86-4bdc-4b39-a6a0-fe922d9b71a1.pdf#page=18 |archive-date=2022-10-09 |url-status=live|title=Dell Inspiron 17 specification}}</ref><ref name=":0">{{Cite web |title=Break/Pause Key No Longer Available on Some Dell XPS, Latitude, and Precision Laptops {{!}} Dell US |url=https://www.dell.com/support/kbdoc/en-us/000145271/break-key-no-longer-available-on-dell-xps-e-and-m-series-portables |access-date=2023-05-05 |website=www.dell.com}}</ref>
*{{keypress|Ctrl|Fn|S}} on some other{{Clarify|date=August 2023}} Dell laptops.<ref name="dellother">{{Cite web|title=Dell community|date=7 January 2012 |url=https://www.dell.com/community/Laptops-General-Read-Only/break-key-alternative/m-p/3826478#M636732}}</ref><ref name=":0" />
* {{keypress|Fn|Esc}} on Samsung.
* {{keypress|Ctrl|Fn|Shift}} on certain HP laptops.
*{{keypress|Fn|Esc}} on Samsung.{{Clarify|date=August 2023}}
* {{keypress|Ctrl|Fn|Shift}} on certain{{Clarify|date=August 2023}} HP laptops.
* {{keypress|Fn|R}} on certain{{Clarify|date=August 2023}} HP laptops.
* {{keypress|Fn|Ctrl|B}} on certain{{Clarify|date=August 2023}} Logitech (LOGI) keyboards.


Substitutes for {{keypress|Pause}}:
Substitutes for {{keypress|Pause}}:
* {{keypress|Fn|P}} or {{keypress|Fn|Ctrl|P}} or {{keypress|Fn|Alt|P}} on certain Lenovo laptops.<ref name="thinkpads1"/>
* {{keypress|Fn|P}} or {{keypress|Fn|Ctrl|P}} or {{keypress|Fn|Alt|P}} on certain{{Clarify|date=August 2023}} Lenovo laptops.<ref name="thinkpads1"/>
* {{keypress|Fn|B}} on certain Dell laptops.<ref name="thinkpads1"/>
* {{keypress|Fn|B}} on certain{{Clarify|date=August 2023}} Dell laptops.<ref name="thinkpads1"/><ref name=":0" />
* {{keypress|Fn|Shift}} on certain HP laptops.
* {{keypress|Fn|Shift}} on certain{{Clarify|date=August 2023}} HP laptops.
* {{keypress|Fn|W}} on certain{{Clarify|date=August 2023}} HP laptops.


⚫
For some{{Clarify|date=August 2023}} Dell laptops, without a {{keypress|Break}} key, press the {{keypress|Alt|Space}} and select "Interrupt".<ref name="DELL">{{cite web|last1=DELL|title=Commonly-Used Keystroke Shortcuts|url=http://www.dell.com/support/article/us/en/19/sln37045/commonly-used-keystroke-shortcuts-technical-tip-162222?lang=en|website=Dell.com|access-date=18 February 2018}}</ref><ref name=":0" />
[[Apple keyboard]]s do not have the Pause/Break key,<ref>Computer Hope, Pause key http://www.computerhope.com/jargon/p/pausekey.htm</ref> as [[Mac OS X]] does not use it{{Original research inline|date=September 2016}}. The key may be substituted by {{keypress|Fn|Esc}}.<ref>Use your Apple Keyboard in Windows Bootcamp https://support.apple.com/en-us/HT202676</ref>

⚫
For some Dell laptops without a Break key press the ALT+Space bar and select "Interrupt". <ref name="DELL">{{cite web|last1=DELL|title=Commonly-Used Keystroke Shortcuts|url=http://www.dell.com/support/article/us/en/19/sln37045/commonly-used-keystroke-shortcuts-technical-tip-162222?lang=en|website=Dell.com|accessdate=18 February 2018}}</ref>


==Usage for breaking the program's execution==
==Usage for breaking the program's execution==
While both {{keypress|Ctrl|Break}} and {{keypress|Ctrl|C}} combination are commonly implemented as a way of breaking the execution of a console application, they are also used for similar effect in [[integrated development environment]]s.<ref>{{cite web|url=http://msdn.microsoft.com/en-us/library/ff540312.aspx |title=CTRL+C (Break) |publisher=Msdn.microsoft.com |date=2010-03-30 |accessdate=2010-10-22}}</ref><ref>{{cite web|url=http://msdn.microsoft.com/en-us/library/ff541727.aspx |title=Debug Break |publisher=Msdn.microsoft.com |date=2010-03-30 |accessdate=2010-10-22}}</ref> Although these two are often considered interchangeable,<ref>{{cite web|url=http://encyclopedia2.thefreedictionary.com/Ctrl-Break |title=Ctrl-Break definition of Ctrl-Break in the Free Online Encyclopedia |publisher=Encyclopedia2.thefreedictionary.com |date= |accessdate=2010-10-22}}</ref> compilers and execution environments usually assign different signals to these.<ref>https://www.gnu.org/software/emacs/windows/ntemacs/discuss/subproc-ctrl-c {{webarchive |url=https://web.archive.org/web/20121022172337/https://www.gnu.org/software/emacs/windows/ntemacs/discuss/subproc-ctrl-c |date=October 22, 2012 }}</ref> Additionally, in some kernels (e.g. miscellaneous DOS variants) {{keypress|Ctrl|C}} is detected only at the time OS tries reading from a keyboard buffer and only if it's the only key sequence in the buffer,<ref>{{cite web|url=http://vimdoc.sourceforge.net/htmldoc/os_dos.html#dos-CTRL-Break |title=Vim documentation: vim online |publisher=Vim.org |date= |accessdate=2010-10-22}}</ref><ref>{{cite web|url=http://www.ousob.com/ng/dos5/ng27979.php |title=ClipX&nbsp;— DOS 5.0 Ref. - int 23h ctrl-c handler |publisher=Ousob.com |date= |accessdate=2010-10-22}}</ref> while {{keypress|Ctrl|Break}} is often translated instantly (e.g. by [[BIOS call|INT 1Bh]] under DOS). Because of this, {{keypress|Ctrl|Break}} is usually a more effective choice under these operating systems; sensitivity for these two combinations can be enhanced by the <code>[[BREAK (CONFIG.SYS directive)|BREAK]]=ON</code> [[CONFIG.SYS]] statement.
While both {{keypress|Ctrl|Break}} and {{keypress|Ctrl|C}} combination are commonly implemented as a way of breaking the execution of a console application, they are also used for similar effect in [[integrated development environment]]s.<ref>{{cite web|url=http://msdn.microsoft.com/en-us/library/ff540312.aspx |title=CTRL+C (Break) |publisher=Msdn.microsoft.com |date=2010-03-30 |access-date=2010-10-22}}</ref><ref>{{cite web|url=http://msdn.microsoft.com/en-us/library/ff541727.aspx |title=Debug Break |publisher=Msdn.microsoft.com |date=2010-03-30 |access-date=2010-10-22}}</ref> Although these two are often considered interchangeable,<ref>{{cite web|url=http://encyclopedia2.thefreedictionary.com/Ctrl-Break |title=Ctrl-Break definition of Ctrl-Break in the Free Online Encyclopedia |publisher=Encyclopedia2.thefreedictionary.com |access-date=2010-10-22}}</ref> compilers and execution environments usually assign different signals to these.<ref>{{cite web |url=https://www.gnu.org/software/emacs/windows/ntemacs/discuss/subproc-ctrl-c |title=Re: trouble passing ^C through to processes running in a *shell* |website=www.gnu.org |archive-url=https://web.archive.org/web/20121022172337/https://www.gnu.org/software/emacs/windows/ntemacs/discuss/subproc-ctrl-c |archive-date=October 22, 2012}}</ref> Additionally, in some kernels (e.g. miscellaneous DOS variants) {{keypress|Ctrl|C}} is detected only at the time OS tries reading from a keyboard buffer and only if it's the only key sequence in the buffer,<ref>{{cite web|url=http://vimdoc.sourceforge.net/htmldoc/os_dos.html#dos-CTRL-Break |title=Vim documentation: vim online |publisher=Vim.org |access-date=2010-10-22}}</ref><ref>{{cite web |url=http://www.ousob.com/ng/dos5/ng27979.php |title=ClipX&nbsp;— DOS 5.0 Ref. - int 23h ctrl-c handler |publisher=Ousob.com |access-date=2010-10-22 |archive-url=https://web.archive.org/web/20160304031501/http://www.ousob.com/ng/dos5/ng27979.php |archive-date=2016-03-04 |url-status=dead }}</ref> while {{keypress|Ctrl|Break}} is often translated instantly (e.g. by [[BIOS call|INT 1Bh]] under DOS). Because of this, {{keypress|Ctrl|Break}} is usually a more effective choice under these operating systems; sensitivity for these two combinations can be enhanced by the <code>[[BREAK (CONFIG.SYS directive)|BREAK]]=ON</code> [[CONFIG.SYS]] statement.

⚫
==References==
⚫
{{reflist}}


==See also==
==See also==
Line 53: Line 53:
*[[Scroll lock]]
*[[Scroll lock]]
*[[Num lock]]
*[[Num lock]]

⚫
==References==
⚫
{{reflist}}

==External links==
*{{Commons category-inline}}

{{Keyboard}}
{{keyboard keys}}
{{keyboard keys}}


Latest revision as of 20:50, 8 May 2024

"Pause button" redirects here. For the media control, see Media controls. For other uses, see Pause.
Break/Pause key on PC keyboard

The Break key (or the symbol ⎉) of a computer keyboard refers to breaking a telegraph circuit and originated with 19th century practice. In modern usage, the key has no well-defined purpose, but while this is the case, it can be used by software for miscellaneous tasks, such as to switch between multiple login sessions, to terminate a program, or to interrupt a modem connection.

Because the break function is usually combined with the pause function on one key since the introduction of the IBM Model M 101-key keyboard in 1985, the Break key is also called the Pause key. It can be used to pause some computer games.

History

[edit]

A standard telegraph circuit connects all the keys, sounders and batteries in a single series loop. Thus the sounders actuate only when both keys are down (closed, also known as "marking" — after the ink marks made on paper tape by early printing telegraphs). So the receiving operator has to hold their key down or close a built-in shorting switch in order to let the other operator send. As a consequence, the receiving operator could interrupt the sending operator by opening their key, breaking the circuit and forcing it into a "spacing" condition. Both sounders stop responding to the sender's keying, alerting the sender (a physical break in the telegraph line would have the same effect).

The teleprinter operated in a very similar fashion except that the sending station kept the loop closed (logic 1, or "marking") even during short pauses between characters. Holding down a special "break" key opened the loop, forcing it into a continuous logic 0, or "spacing", condition. When this occurred, the teleprinter mechanisms continually actuated without printing anything, as the all-0s character is the non-printing NUL in both Baudot and ASCII. The resulting noise got the sending operator's attention.

This practice carried over to teleprinter use on time-sharing computers. A continuous spacing (logical 0) condition violates the rule that every valid character has to end with one or more logic 1 (marking) "stop" bits. The computer (specifically the UART) recognized this as a special "break" condition and generated an interrupt that typically stopped a running program or forced the operating system to prompt for a login. Although asynchronous serial telegraphy is now rare, the Break key once used with terminal emulators can still be used by software for similar purposes.

Sinclair

[edit]

On the ZX80 and ZX81 computers, the Break is accessed by pressing Space. On the ZX Spectrum it is accessed by Caps Shift+Space. The Spectrum+ and later computers have a dedicated Break key. It does not trigger an interrupt but will halt any running BASIC program, or terminate the loading or saving of data to cassette tape. An interrupted BASIC program can usually be resumed with the CONTINUE command. The Sinclair QL computer, without a Break key, maps the function to Ctrl+Space.

BBC Micro

[edit]

On a BBC Micro computer, the Break key generates a hardware reset which would normally cause a warm restart of the computer. A cold restart is triggered by pressing Ctrl+Break. If a filing system is installed, ⇧ Shift+Break will cause the computer to search for and load or run a file called !Boot on the filing system's default device (e.g. floppy disk 0, network user BOOT). The latter two behaviours were inherited by the successor to Acorn MOS, RISC OS. These behaviours could be changed or exchanged in software, and were often used in rudimentary anti-piracy techniques.

Because of the BBC Micro's near universal usage in British schools, later versions of the machine incorporated a physical lock on the Break key to stop children from intentionally resetting the computer.

Modern keyboards

[edit]

On many modern PCs, Pause interrupts screen output by BIOS until another key is pressed. This is effective during boot in text mode and in a DOS box in Windows safe mode with 50 lines. On early keyboards without a Pause key (before the introduction of 101/102-key keyboards) the Pause function was assigned to Ctrl+NumLock, and the Break function to Ctrl+ScrLock; these key-combinations still work with most programs, even on modern PCs with modern keyboards. Pressing the dedicated Pause key on 101/102-key keyboards sends the same scancodes as pressing Ctrl, then NumLock, then releasing them in the reverse order would do; additionally, an E1hex prefix is sent, which enables 101/102-key-aware software to discern the two situations, while older software usually just ignores the prefix. The Pause key is different from all other keys in that it sends no scancodes at all on release in PS/2 modes 1 or 2, so it is impossible to determine whether this key is being held down with older devices. In PS/2 mode 3 or USB HID mode, there is a release scancode, so it is possible to determine whether this key is being held down on modern computers.[1]

On modern keyboards, the Break key is usually labeled Pause with Break below, sometimes separated by a line: ⁠Pause/Break⁠, or Pause on the top of the keycap and Break on the front, or only Pause without Break at all. In most Windows environments, the key combination ⊞ Win+Pause brings up the system properties.

Keyboards without Break key

[edit]

Compact and notebook keyboards often do not have a dedicated Pause/Break key.

Substitutes for Break:

Substitutes for Pause:

For some[clarification needed] Dell laptops, without a Break key, press the Alt+Space and select "Interrupt".[8][6]

Usage for breaking the program's execution

[edit]

While both Ctrl+Break and Ctrl+C combination are commonly implemented as a way of breaking the execution of a console application, they are also used for similar effect in integrated development environments.[9][10] Although these two are often considered interchangeable,[11] compilers and execution environments usually assign different signals to these.[12] Additionally, in some kernels (e.g. miscellaneous DOS variants) Ctrl+C is detected only at the time OS tries reading from a keyboard buffer and only if it's the only key sequence in the buffer,[13][14] while Ctrl+Break is often translated instantly (e.g. by INT 1Bh under DOS). Because of this, Ctrl+Break is usually a more effective choice under these operating systems; sensitivity for these two combinations can be enhanced by the BREAK=ON CONFIG.SYS statement.

See also

[edit]

References

[edit]
  1. ^ "Keyboard 101- and 102-Key". PS/2 Hardware Interface Technical Reference (PDF). IBM. October 1990. p. 19. Archived (PDF) from the original on 2022-10-09. Except for the Pause key, all keys are make/break.
  2. ^ "Keyboard shortcut for Break, Pause, ScrLK, SysRq function on ThinkPad 6 rows Precision keyboard - ThinkPad - Lenovo Support US".
  3. ^ "Ctrl-Break key - Thinkpads Forum".
  4. ^ a b c "T530 Pause/Break key - Thinkpads Forum".
  5. ^ "Dell Inspiron 17 specification" (PDF). Archived (PDF) from the original on 2022-10-09.
  6. ^ a b c d "Break/Pause Key No Longer Available on Some Dell XPS, Latitude, and Precision Laptops | Dell US". www.dell.com. Retrieved 2023-05-05.
  7. ^ "Dell community". 7 January 2012.
  8. ^ DELL. "Commonly-Used Keystroke Shortcuts". Dell.com. Retrieved 18 February 2018.
  9. ^ "CTRL+C (Break)". Msdn.microsoft.com. 2010-03-30. Retrieved 2010-10-22.
  10. ^ "Debug Break". Msdn.microsoft.com. 2010-03-30. Retrieved 2010-10-22.
  11. ^ "Ctrl-Break definition of Ctrl-Break in the Free Online Encyclopedia". Encyclopedia2.thefreedictionary.com. Retrieved 2010-10-22.
  12. ^ "Re: trouble passing ^C through to processes running in a *shell*". www.gnu.org. Archived from the original on October 22, 2012.
  13. ^ "Vim documentation: vim online". Vim.org. Retrieved 2010-10-22.
  14. ^ "ClipX — DOS 5.0 Ref. - int 23h ctrl-c handler". Ousob.com. Archived from the original on 2016-03-04. Retrieved 2010-10-22.
[edit]
  • Media related to Break key at Wikimedia Commons
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
TildeExclamation markAt signNumber signDollar signPercent signCaretAmpersandAsteriskParenthesisParenthesisUnderscorePlus signBackspaceBacktick1 (number)2 (number)3 (number)4 (number)5 (number)6 (number)7 (number)8 (number)9 (number)0Hyphen-minusEquals signBackspaceTab keyQWERTYUIOPCurly bracketCurly bracketVertical barTab keyQWERTYUIOPSquare bracketSquare bracketBackslashCaps lockASDFGHJKLColon (punctuation)Quotation markEnter keyCaps lockASDFGHJKLSemicolonApostropheEnter keyShift keyZXCVBNMBracketBracketQuestion markShift keyShift keyZXCVBNMComma (punctuation)Full stopSlash (punctuation)Shift keyControl keyWindows keyAlt keySpace barAlt keyWindows keyMenu keyControl key
 Insert Home PgUp Num
Lock 		∕ ∗ −
Delete End PgDn 7 8 9 +
4 5 6
↑ 1 2 3 Enter
← ↓ →    0
   Ins 		 . 
Del
Retrieved from "https://en.wikipedia.org/w/index.php?title=Break_key&oldid=1222932955"