As far as I know, VESA graphics mode numbers are not standardized,
which is why the vesa info block of standard 1.2 and higher, returned
by INT 10h function AX=4F00h, contains a mode list, which you then
need to traverse using INT10h AX=4F01. So as a first step I'd check if
the watcom graphics library does that. As a first test you might want
to use the 'listvesa' package from the FreeDOS Live-CD (utilities
section IIRC) to see if your graphics card does support at least VESA
1.2 and then if it supports that specific mode.
cheers, Hippo
On Fri, 27 Oct 2023 at 01:18, Jim Hall via Freedos-devel
<freedos-devel@lists.sourceforge.net> wrote:
>
> On Wed, Oct 25, 2023 at 5:58 AM Walter Oesch via Freedos-devel
> <freedos-devel@lists.sourceforge.net> wrote:
> >
> > From Code:
> >
> > if(_setvideomode(_SRES16COLOR) == 0) /* Switch to 800*600 mode with
> > 16 colors */
> > {
> > printf("\n\nVideo mode not supported!!!\n");
> > printf("Maybe the VESA driver has not been loaded!\n");
> >
> >
> > There must be used VESA driver.
> >
>
>
>
> If it helps to have a quick test program to try on your board, you can
> find GRAFTEST.EXE here:
>
> https://personal.freedos.org/temp/GRAFTEST.EXE
>
>
> This just puts the display into graphics mode then draws a square,
> circle, and diagonal line. The EXE is compiled with OpenWatcom C using
> the defaults (using "WCL -q GRAFTEST.C") so it's without optimization
> - it's just a demo program. Source code is in GRAFTEST.C (at same
> location, also copied below)
>
>
> #include <stdio.h>
> #include <conio.h> /* getch */
> #include <graph.h> /* graphics mode */
>
> int main()
> {
> if (_setvideomode(_VRES16COLOR) == 0) {
> puts("cannot set video mode");
> return 1;
> }
>
> /* draw shapes */
>
> _setcolor(1); /* blue */
> _rectangle(_GFILLINTERIOR, 50,75, 350,375); /* from 50,75 to 350,375 */
>
> _setcolor(2); /* green */
> _ellipse(_GFILLINTERIOR, 300,200, 500,400); /* from 300,200 to 500,400 */
>
> _setcolor(15); /* br white */
> _moveto(10,10);
> _lineto(600,400); /* line from 1,1 to 600,400 */
>
> if (getch() == 0) {
> /* if getch is zero, then extended key. call getch again to clear
> it and get a new extended code */
> getch(); /* but we don't really need it anyway :-) */
> }
>
> /* done */
>
> _setvideomode(_DEFAULTMODE);
> return 0;
> }
>
>
>
> (my code formatting may be messed up when copied/pasted into an email)
>
> I'll delete the https://personal.freedos.org/temp/ URL around November 1.
>
>
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> Freedos-devel@lists.sourceforge.net
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