Messages in this thread |  | | Date | Wed, 3 Jan 2001 16:39:11 +0100 (MET) | From | "Maciej W. Rozycki" <> | Subject | Re: Timeout: AT keyboard not present? |
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On Wed, 3 Jan 2001 Andries.Brouwer@cwi.nl wrote:
> (Ordinarily a key-up event gets scancode of key-down but with > high-order bit set. In scancode set 1, a key-up event get the > scancode of key-down prefixed by 0xf0. Since the high-order bit > is masked here, this 0xf0 would show up as 0x70. > Moreover, the key-up for a sequence like e0 71 is e0 f0 71, > again what you see here.) > > How you got into scancode mode 1 I don't know > (maybe by sending the command f0 01 to the keyboard).
It looks like untranslated mode 2 (i.e. the AT keyboard's mode). You switch translation on or off by toggling a bit in the onboard 8042's command byte.
PS/2-style keyboards start in mode 2 usually. An XT compatibility (bit 7 meaning release) is provided by the onboard 8042 translating codes. Some systems (I think DEC OSF/1, for example) program keyboards to work in mode 3 (the PS/2 native mode) or possibly mode 1 (XT compatibility mode); for these modes the 8042's translation has to disabled or the keyboard will be next to useless. It's also meaningful to disable the translation in mode 2 -- you are presented with the AT interface then.
-- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
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