Comments by "Lawrence D’Oliveiro" (@lawrencedoliveiro9104) on "How Software Deals with Key Presses - Computerphile" video.

  1. 4:05 Not just a security issue: think about languages that require a front-end processor (e.g. Chinese/Japanese/Korean) to translate keystrokes into a large character set: putting this in userland makes it more flexible, replaceable, configurable etc.
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  2. That was discussed in part 1. It’s why the matrix is scanned, not simply fed with static voltages.
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  3. There’s nothing special at the hardware level to distinguish modifier from non-modifier keys--this is just a software convention. For example, in Blender 2.79, you can hold the D key down to draw with the Grease Pencil, or the K key and drag to cut with the knife tool.
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  4. 10:05 With Linux, was that measured in a GUI window (which GUI?) or in a text console?
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  5. 4:05 Another issue is the handling of autorepeat: by having this entirely in software, you don’t actually have to insert the repeated keystrokes into any buffers; you simply generate them on demand, as the user program asks for keystrokes. That way, you never have them happening faster than the program can handle.
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