Re: Bare metal text I/O in Ada

["John McCormick" <mccormick@cs.uni.edu>]

I do have access to the BIOS.  But my application runs in protected
mode.  I am starting to gather up some documentation on VGA and will
try to see if I can access the video memory directly.  I know that I
can access the I/O ports in protected mode.

A silver lining to the whole thing is that the keyboard problem might
make a good exercise to introduce my students to Ada interrupt
handling.

John

Randy Brukardt wrote:
> <tmoran@acm.org> wrote in message
news:M5Kdna9J29x7W6DfRVn-3g@comcast.com...
> > >keyboard input and text output to EGA / VGA on a bare metal (no
> > >operating system) AMD (Intel clone) platform.
> >   No PC-style BIOS ROM either?
>
> If you have access to the BIOS ROM, it's pretty easy. But the BIOS
doesn't
> function in protected mode, and most compilers these days are 32-bit
> protected.
>
> One possibility would be write some code to call the BIOS, switching
modes
> as needed. That's how DOS-Extenders worked, and they're not that
> complicated. Debugging the code might be fun, though. It certainly
would be
> better to access to the BIOS than to write new drivers for the
keyboard and
> video screen (which would essentially be a copy of the BIOS).
>
> I can help you with the BIOS calls needed (our text windowing package
did
> this for all of its I/O), but we always assumed the existence of a
DOS
> Extender.
> 
>                            Randy Brukardt