[comp.sys.ibm.pc.misc] Tpascal's

hannes@complx.UUCP (Johannes Kiehl) (04/10/91)

Hi folks ,

   here's another problem with a rather sumptuos Turbo-Pascal-(5.5)-
project.
   The program, which features a (home-brewed) graphical user
interface, runs comparably well on the Hercules card, for which it was
developped. Quite a while ago, though, I wrote a colour version for
the EGA, and that was when the hassle began.
   A user can force the program to temporarily quit the graphics mode
(I tried both "restorecrtmode" and "closegraph") by invoking a DOS
command shell. Afterwards, the graphics screen is rebuilt, and this is
done rather by redrawing than by moving memory blocks around (so
there's no extra heap space occupied at that time).
   Now the EGA version refuses to re-enter the graphics mode using
again "initgraph (gd=3,gm=1,path)". Instead, I'm getting varying 
runtime errors, including the infamous ".BGI driver not present",
"Graphics not initialized", "Graphics Hardware not detected" and many
more (it goes whithout saying that this wouldn't happen with smaller 
test programs I wrote).
   Borland's Munich Hotline suggested that this might point to memory
problems; they said, the graph unit didn't check heap and stack space
and react as described, if one of them was too cramped. I think they
must be right in some way. Yet increasing those didn't change
anything; and even a stack offset of 55000 and a heap of 100K at the
time of the initgraph complained about wouldn't cure the disease.
   I've got to mention that the .BGI files (HERC and EGAVGA) weren't
linked into the .EXE until lately. Now that I've linked them in, the
program won't even start, showing the same symptoms as described!
Again, the new Hercules version works perfectly.
I'm extensively using the overlay unit, if that's of any significance.
   I'd appreciate any help on this, and of course I promise to
summarize to the net, if I should receive a hint that hits. Oh, and...
please use the *.de address when replying from the US.

hannes.

--
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 &HP'ZNF'      Johannes Kiehl
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 ?ZHXMZ%_      kiehl@helg.informatik.uni-stuttgart.de *)
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