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SubjectRe: Input issues - key down with no key up
On Sun, 17 Aug 2003, Vojtech Pavlik wrote:

> > What are the known problems with mode #3, then?
> It's broken on many keyboards (on some only slightly, like some keys not
> working properly). Other (special, either unix workstation or point of
> sale) keyboards need it to work properly.

IIRC, OSF/1 running on later Alphas with a PS/2 keyboard interface
(earlier oned had an LK201 one) uses mode #3. I can't comment on the VMS.

> > That is, why doesn't everyone use it and why haven't they always used it?
> Because old AT keyboards didn't support it. Because the XT keyboard
> didn't support it. Because history sticks.

Since the 8042+keyboard combo supports a PC/XT compatibility mode there
was no incentive -- why bother modifying software if the hardware works
with the old one? Even if that sucks.

> > For that matter, what does Windows use?
> Translated Set 2. Actually an emulated XT keyboard.

For mode #3 explicit handling for hot-plugging would be required -- I
guess the change would be much too intrusive. And untranslated mode #2 is
nearly the same as an emulated PC/XT keyboard: codes are different and the
release bit is replaced by the release code, but the multibyte mess for
PS/2-specific keys remains -- no gain at all.

+ Maciej W. Rozycki, Technical University of Gdansk, Poland +
+ e-mail:, PGP key available +

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