On 12/16/2019 10:00 AM, Lino Mastrodomenico wrote:
Despite some limitations the nice thing about setting high-res text
modes using only generic VGA registers (as opposed to card-specific
SuperVGA) is that the same code works ~everywhere and doesn't need a
VBE BIOS; the downside is that the VGA pixel clock frequency is too
low for high resolution, so traditional graphics cards and CRT screens
will not work correctly, but emulators and some laptop graphics cards
seem fine.
I'm considering adding support for these modes to FreeDOS mode.com
<http://mode.com> but before I propose a patch I wanted to check if
there's something similar and open source out there.
The basic problem is that this doesn't work as you intend. Even the
extended text modes via "generic VGA registers" doesn't work on newer
hardware anymore, nor do all emulators support those tricks (properly).
In general, there is a lot of hit and miss when trying that. I know this
out of first hand experience, as I used to use extended/non-standard
text modes in several of my own programs "back in the days", including
having my own text mode tool. But for example on my current Dell Dual
Core laptop, most of these modes won't work, because the graphics chip
(in this case part of the Intel CPU) is not 100% register compatible to
old VGA cards. And also VirtualBox doesn't like a lot of those tricks,
regardless of the version...
Ralf
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