IBM Model M Pause/Break key won't stay pressed

[globby]

I've got a Model M keyboard, manufactured Dec 14, 1990. All of the keys work, but the Pause/Break key will only register momentarily.

EK Switch Hitter shows that holding down Pause registers a release in 8ms. Holding a Control key down and then holding down Pause/Break registers a release in 6ms - 7ms.

This is such specifically odd and consistent behavior, I wonder if it's by design. Did the Model M circuitry not allow the user to hold down the Pause/Break key?

ModelM-PauseBreakKey.png (63.86 KiB) Viewed 1589 times

[depletedvespene]

This is indeed by design. The Pause key was originally meant to immediately pause the text scrolling in the monitor (scrollback did not exist), so its functionality had to be activated immediately, not even waiting for the user to release the key.

[globby]

Great, thank you! It makes sense, but I don't think I've seen another keyboard with this behavior.

[Muirium]

This rings a distant bell. It may be only IBM's own keyboards (and their stock controllers) actually did this. I remember encountering it at one point while writing my multi-keyboard Soarer configuration. Haven't used a Model M with a stock controller in quite a while, though. Maybe one to try out on my (awaiting F conversion) SSK.