Wow, many thanks for the analysis, I'm impressed!
I'll try to build a patching DISPLAY asap.

Aitor

2006/10/16, Joris van Rantwijk <[EMAIL PROTECTED]>:
> Hello Aitor,
>
> Aitor Santamaría wrote:
> > Perhaps you could try 850 or 858, at least one of them should be there
> > (850 is the western european typical codepage, 858 is the same but
> > with the Euro sign).
>
> I tried all three codepages, and none of them work.
> Although in Qemu, with CON=(EGA,,1), all three codepages work.
>
> After reading bits of assembler code and bits of CPI file, I have a
> theory that may explain the situation:
>
> - The CGA specific driver initializes the global variable wNumSubFonts
> to 1 (see display/egavga/cgaega.asm line 239).
> - The font-reading code takes this as a signal that it should only
> consider the first subfont in a codepage. If that first subfont is not
> of correct size, it assumes that the whole codepage is screwed (see
> display/egavga/egar.asm lines 302 and further).
> - But in EGA.CPX the first subfont is size 16, followed by size 14,
> followed by size 8. So the font reader gives up before it finds the
> subfont of the right size.
>
> ... Wow! I just found some evidence in support of the above theory. With
> a binary patch to DISPLAY.EXE, to make it skip over nonsupported
> subfonts, it is now able to load the codepage on CGA.
>
> I can now also confirm that GRAFTABL emulation works; I can see the
> linedrawing characters in graphics mode :-). Of course the codepage does
> not affect CGA text mode, but it works for graphics. Oh I've never seen
> such an ugly euro sign ;-)
>
> Bye,
>  Joris.
>
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