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Post by rossd on Apr 23, 2021 17:49:20 GMT 1
I am very impressed with vDos and have solved many issues in getting it to work with my software and hardware
using the config.txt instructions. But one issue I can't resolve is a program that displays text screens
properly but when it switches to a screen of mixed text and graphics only the graphic characters display.
In the underlying MS Basic program a SCREEN 9 command to enable 80 x 25 or 80 x 43 text and 640 x 350 graphics
in a EGA or VGA adapter mode seems to turn off text rather than enable it. Even text-only screens that work
originally show no text after a SCREEN 9 command is encountered in the program. I have loaded the Consola
font to the vDos area and tried the minus sign in front of it. But nothing seems to permit the simultaneous
display of text and graphics. (My screen resolution is 1920 x 1200.) Suggestions please?
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Post by Jos on Apr 23, 2021 19:11:08 GMT 1
Video adapters have two distinct operating modes: Text-only and graphics, those don’t mix. In graphics mode, a program displays the characters pixel by pixel. It of course has to draw the correct representation of the characters. Those bitmap representations can be embedded in the program, or it uses those defined in the ROM memory of the video adapter. It then has to know where the bitmaps, for instance 8x14 (80x25 at 640x350) are stored. Inquiring that location in a certain way goes wrong in the current vDos version, but is fixed in the 2021.05.01 version.
Selecting a specific text mode by a program doesn’t work in vDos. It is fixed at that defined in config.txt, and not restricted to the few the video BIOS supports. Most programs that support something else than 80x25 will also detect and support the dimensions that can be set in config.txt. If not, you have to set one in config.txt that is supported, and eventually set that in the program.
Setting a different front in config.txt, or a minus sign in front only applies to text mode. As said, the programs draw the characters itself in graphic mode. That's the reason why text (in text mode) will be displayed in more detail (quality) at higher resolutions. And graphics just becomes more blockery.
Jos
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Post by rossd on Apr 23, 2021 21:29:41 GMT 1
Hi Jos,
The Consola font is called for in config.txt to be sure a TTF font was used, not specified in the program. The program in question does work properly in original DOS and the version that XP makes available. I look forward to seeing if your 2021.05.01 version may resolve this issue. Thank you.
rossd
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Post by Jos on Apr 23, 2021 21:57:06 GMT 1
Your program can’t control the font vDos uses in text mode.
If you don’t specify an external font in config.txt, the embedded vDos font is used.
Also a TTF font, but optimized for DOS apps.
Consolas isn’t, and will for instance display blank lines at some resolutions.
The internal font also facilitates line drawing character substitution to get a more modern appeal.
Jos
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Post by rossd on Apr 23, 2021 22:43:51 GMT 1
Removing the Consola font line from config.txt does result in a text font with a nice appearance, but does not resolve the disappearing text problem.
rossd
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Post by Jos on Apr 23, 2021 23:14:19 GMT 1
As said, in graphic mode a DOS program draws the characters pixels by pixel.
vDos can’t ‘magically’ turn that in something else (better). Only in text mode, where the program stores the ASCII value and colors of a character in the video memory.
For the disappearing text in graphic mode you’ll have to wait for the next vDos released (May 1st).
Jos
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