From:	jce AT seasip DOT demon DOT co DOT uk (John Elliott)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Running multiple DJGPP apps from 16-bit
Date:	Tue, 13 Oct 1998 21:58:41 GMT
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

  Quite recently, I managed to port Digital Research's GEM bindings to 
DJGPP, so that it can be used to write GEM apps (the apps are 32-bit DJGPP
programs, while GEM remains a 16-bit real-mode GUI). When I released the 
library, it couldn't do Desk Accessories.

  I have now managed to write a suitable stub for Desk Accessories. However,
GEM can only run one protected-mode program at a time. If I have a
protected-mode DA loaded, I can't then run a protected-mode app.

  As far as I can see, this is because GEM does context switches in 16 bits,
and tries to load the application while the DA is in the middle of a 
__dpmi_int() call.

 - GEM loads a protected-mode DA.
 - The DA enters its event loop, and calls GEM with __dpmi_int().
 - Since the DA's event queue is empty, GEM switches context to its desktop.
 - The desktop starts a protected-mode application, by loading its real-mode
  stub (INT 21 AH=4Bh)

  Using CWSDPMI, I get a crash when the application starts. Using the DRDOS
DPMI host (7.03), I get a crash when the application terminates.

  Am I trying something completely impossible here, or is there any way to
get round this?

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John Elliott           |BLOODNOK: "But why have you got such a long face?"
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