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Q&A Why is Pause/Break key is immediately released? Can that be fixed?

From Wikipedia: Break key: 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 ...

posted 3y ago by Quasímodo‭  ·  edited 3y ago by Quasímodo‭

Answer
#3: Post edited by user avatar Quasímodo‭ · 2022-02-16T12:37:42Z (almost 3 years ago)
Add Wikipedia and IBM documents
  • In [Keyboard scancodes](https://www.win.tue.nl/~aeb/linux/kbd/scancodes-1.html), Andries E. Brouwer says:
  • > The latter [Pause/Break key] produces scancode sequence e1 1d 45 e1 9d c5 when pressed (without modifier) and nothing at all upon release.
  • Since that is exactly what I get from `showkey -s` I guess it must be true and thus Pause/Break really cannot be used as a modifier.
  • [TLDP: The Linux keyboard and console: Unusual keys and keyboards](https://tldp.org/HOWTO/Keyboard-and-Console-HOWTO-14.html) reiterates:
  • > The Pause/Break key is also special in another way: it does not generate key-up scancodes, but generates the entire 6-scancode sequence on key-down.
  • From [Wikipedia: Break key](https://en.wikipedia.org/wiki/Break_key#Modern_keyboards):
  • > 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.
  • The claim is backed up by [IBM: "Keyboard 101- and 102-Key". PS/2 Hardware Interface Technical Reference.](http://www.mcamafia.de/pdf/ibm_hitrc11.pdf)
  • In [Keyboard scancodes](https://www.win.tue.nl/~aeb/linux/kbd/scancodes-1.html), Andries E. Brouwer says:
  • > The latter [Pause/Break key] produces scancode sequence e1 1d 45 e1 9d c5 when pressed (without modifier) and nothing at all upon release.
  • That is exactly what I get from `showkey -s`.
  • [TLDP: The Linux keyboard and console: Unusual keys and keyboards](https://tldp.org/HOWTO/Keyboard-and-Console-HOWTO-14.html) reiterates:
  • > The Pause/Break key is also special in another way: it does not generate key-up scancodes, but generates the entire 6-scancode sequence on key-down.
  • All in all, **Pause/Break really cannot be used as a modifier** in my keyboard setup, since this is a hardware limitation.
#2: Post edited by user avatar Quasímodo‭ · 2022-01-14T14:47:30Z (almost 3 years ago)
  • In [Keyboard scancodes](https://www.win.tue.nl/~aeb/linux/kbd/scancodes-1.html), Andries E. Brouwer says
  • > The latter [Pause/Break key] produces scancode sequence e1 1d 45 e1 9d c5 when pressed (without modifier) and nothing at all upon release.
  • Since that is exactly what I get from `showkey -s` I guess it must be true and thus Pause/Break really cannot be used as a modifier.
  • In [Keyboard scancodes](https://www.win.tue.nl/~aeb/linux/kbd/scancodes-1.html), Andries E. Brouwer says:
  • > The latter [Pause/Break key] produces scancode sequence e1 1d 45 e1 9d c5 when pressed (without modifier) and nothing at all upon release.
  • Since that is exactly what I get from `showkey -s` I guess it must be true and thus Pause/Break really cannot be used as a modifier.
  • [TLDP: The Linux keyboard and console: Unusual keys and keyboards](https://tldp.org/HOWTO/Keyboard-and-Console-HOWTO-14.html) reiterates:
  • > The Pause/Break key is also special in another way: it does not generate key-up scancodes, but generates the entire 6-scancode sequence on key-down.
#1: Initial revision by user avatar Quasímodo‭ · 2021-10-24T15:06:36Z (about 3 years ago)
In [Keyboard scancodes](https://www.win.tue.nl/~aeb/linux/kbd/scancodes-1.html), Andries E. Brouwer says

> The latter [Pause/Break key] produces scancode sequence e1 1d 45 e1 9d c5 when pressed (without modifier) and nothing at all upon release.

Since that is exactly what I get from `showkey -s` I guess it must be true and thus Pause/Break really cannot be used as a modifier.