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In reply to : Bret 'll have to hate FreeDOS mKEYB, too (Developers)

posted by Rugxulo Homepage, Usono, 19.05.2011, 22:42
(edited by Rugxulo on 21.05.2011, 00:58)

> > If the user (or a program) tries to change the code page to one
> > your driver doesn't support, and you don't respond appropriately, you
> > could be in trouble. If you don't monitor INT 2F.2D81, you must instead
> > poll the system to determine the current code page each time you perform
> a
> > scancode-to-ASCII translation, at least for ASCII characters > 127.
>
> agreed. mKEYB is lazy in this regard, and ignores codepages completely.
> (the 'm' stands for 'mini')
>
> the 'official' FreeDOS KEYBhandles codepages (for a bazillion languages)
> but is a bit larger. I'll stick with mKEYB.

<boring useless trivia nobody cares about but me>

Just for the record (though it doesn't majorly matter), to change the currently selected "display" codepage:

MS-DOS, DR-DOS: int 21h 440Ch 6Ah
MS-DOS, FreeDOS: int 2Fh, 0AD02h

Yes, int 2Fh 0AD02h is "documented" in RBIL, but it's the low-level (hidden) interface, I think. FreeDOS doesn't support the other way because that's IOCTL and their DISPLAY is an TSR (.EXE), not a device driver (.SYS) (and Aitor is strict about that separation).

Long story short, for ultimate compatibility, you'd (in theory) want to support both. BUT, in reality, it's almost impossible to write for what you can't test (and although DR-DOS is fairly cheap, it ain't free nor libre, which I'm sure lessens its appeal greatly).

So whatever, don't worry about it too hard. But the moral of the story is you have to test everywhere and not blindly rely on what you think, as even RBIL is underdocumented or incorrect in a few places. (It didn't mention DR-DOS specifically here anyways, plus cp853 is undocumented for them, has a bug/missing char, and it's not "Latin-2" but instead Latin-3. Apparently nobody ever cared to support all Latin 1-4 despite them being designed at the same time. So much for standards, esp. obsolete ones, heh.)

</boring useless trivia nobody cares about but me>

EDIT: Corrected accidental error, sorry for the confusion.

 

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