[Coco] : GIME text modes and font data

[Robert Gault]

William Astle wrote:
> Okay, I need to call everyone on this even though I know it's going to stir up a
> flame war. Almost nobody who has responded thus far has demonstrated that they
> actually read my original query completely.
>
> My question was simple. Where does the font data come from when the GIME is
> displaying a hardware text mode.
>
> The answer to the original question appears to be "the font data used by the
> GIME in hardware text modes is internal to the GIME". This is what I originally
> thought for various reasons related to design complexity, etc.
>
> As explained in my original message, my confusion came from the fact that at
> least some versions of Mess do things differently - that is, they take the font
> data for the hardware text modes from the HPRINT font data in the 32K internal
> ROM. This is almost certainly the wrong thing to do given the preceding answer
> and it looks like later versions have attempted to correct that deficiency.
>
> Now don't get me wrong, there has been some good information which will likely
> be of use to others, including descriptions of how the various resolution and
> mode settings interact and so on. However, none of that is relevant to my
> original question and if I did not already understand basically how it all
> works, it would only have served to confuse me further.
>
>

William,

If you are unhappy with the answers received so far, look at your original 
message. You did not indicate which version of MESS you used, so it was not 
possible to test your MESS problems. Since you seem to have been more interested 
in MESS than a real Coco3, your question might have been better addressed to the 
MESS BBS at
http://forums.bannister.org/ubbthreads.php?ubb=postlist&Board=1

If you look at the Coco3 service manual on page 96, you will see a block 
schematic of the GIME chip. It contains a block labeled "CHAR GEN ROM", 
indicating that any characters used on the 40/80 text screens use data from 
within the GIME.
Regarding MESS, I've tested the versions .134 and .146u5 by altering the HPRINT 
! and neither one has the ! character changed on a 40/80 text screen if I make 
the entry $00s in the coco3.rom. That means neither of these versions use the 
HPRINT data in the coco3.rom for text screens.

The source code for r146u5 has the table

//-------------------------------------------------
//  hires_font
//-------------------------------------------------

const UINT8 gime_base_device::hires_font[128][12] =

at the end of the file src\mess\video\gime.c. That is exactly where you might 
expect it to be when emulating a "CHAR GEN ROM" contained within the GIME.

Now back to your original message. If you want help with altering the "hardware" 
GIME text data, you will need to report exactly what you did and with which 
version of MESS. Clearly you would either need to compile a new version of MESS 
with altered source code or patch either mess.exe or messui.exe.