To: Kimberley Burchett <OKRA AT max DOT tiac DOT net>
Cc: DJGPP Mailing List <djgpp AT sun DOT soe DOT clarkson DOT edu>
Subject: Re: timer int 
Date: Tue, 10 Jan 95 08:31:40 +0200
From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>

>> ... and you installed your TimerInternalHandler() as what?  Real-mode
>> handler, protected-mode handler or both?
>
>  pmode handler with an iret wrapper and a real mode iret callback.

Real-mode iret callbacks are buggy in DJGPP 1.12m2.  The problem is
in the allocated wrapper function which doesn't do everything it should
the way it should.  If you work under DPMI (Windows, QDPMI or some such),
you can only install a protected-mode handler, because in DPMI hardware
interrupts are always reflected to protected mode first.  If not, I'm
afraid you will have to do it right yourself.  Looking into fsdb104
code, which handles interrupt-driven serial communications, might help,
though.