DOS ain't dead

International keyboard support (Developers)

posted by Aitor, 06.03.2023, 01:09

> Understood about the difference between the display code page and the
> keyboard layout. I know this, but not everything comes across in a web
> forum posting.
>
> I'm using text mode because I am targeting CGA text mode on slow machines,
> and the graphics modes for those machines would never be usable. CGA and
> MDA users will be limited to CP437. The same code has to run everywhere
> because I don't have the time to do multiple versions. EGA and VGA users
> might have a different code page loaded, so I don't want to make
> assumptions about what they have loaded, hence the need for a flexible
> mapping from whatever codepage is loaded to Unicode.

Hi,

just to add a couple of things: I think it is clearly stated that KEYB will just drop characters to the keyboard buffer, simply a list of characters to be "read" by the console or whatever the program that waits for user keyboard imput.

The fact that KEYB understands of "codepages" means that if you are pressing the key to produce À, it may be in different position for different codepages, hence it drops different numbers.

If it were a question of the number of bytes posted by KEYB, there would be a shaky and painful way of doing it: in FD-KEYB you can define "strings", and therefore make the keyboard drop more than one byte per a key-press.

However, you still need that someone (usually the screen BIOS) will translate characters into glyphs. Should you have a program that is able to read UTF or any other multi-byte characters from the keyboard buffer, it could translate it into the appropriate way, but you would still need a graphics mode if you wanted to output more than 256 (or 512) bytes.

If you planned to enlarge the output to 512 characters (instead of 256 character codepage tables), IIRC you would be loosing the ability of the screen BIOS to use light colours as background colour. Some programs may misbehave, as they may expect to use light background colours.

Anyway in CGA you can just use 8x8 character glyphs.

There aren't many chances to go Unicode with a CGA card, I'm afraid.

Aitor

Complete thread:

• International keyboard support - mbbrutman, 21.01.2023, 21:44 (Developers)
  • International keyboard support - marcov, 22.01.2023, 14:19
  • International keyboard support - tom, 22.01.2023, 18:06
  • International keyboard support - Laaca, 22.01.2023, 21:55
    • International keyboard support - mbbrutman, 22.01.2023, 22:46
      • International keyboard support - Laaca, 23.01.2023, 00:20
      • International keyboard support - bretjohn, 23.01.2023, 18:12
        • International keyboard support - mbbrutman, 23.01.2023, 23:51
          • International keyboard support - bretjohn, 24.01.2023, 21:10
        • International keyboard support - tom, 12.02.2023, 18:39
          • International keyboard support - bretjohn, 13.02.2023, 15:35
            • International keyboard support - tom, 13.02.2023, 18:36
              • International keyboard support - bretjohn, 14.02.2023, 04:51
            • International keyboard support - tkchia, 13.02.2023, 20:13
              • International keyboard support - bretjohn, 14.02.2023, 05:05
      • International keyboard support - tom, 14.02.2023, 12:17
        • International keyboard support - tom, 15.02.2023, 13:19
          • International keyboard support - marcov, 15.02.2023, 18:14
            • International keyboard support - tom, 15.02.2023, 21:31
              • International keyboard support - mbbrutman, 18.02.2023, 03:17
                • International keyboard support - Aitor, 06.03.2023, 01:09