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From: ralf@b.gp.cs.cmu.edu (Ralf Brown)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Background Communications under Desqview
Message-ID: <2609@pt.cs.cmu.edu>
Date: 5 Aug 88 21:29:30 GMT
References: <595@unh.UUCP> <2706@bgsuvax.UUCP> <7804@cup.portal.com> <380@eecea.eece.ksu.edu>
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Organization: Carnegie-Mellon University, CS/RI
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In article <380@eecea.eece.ksu.edu> gordon@eecea.UUCP (Dwight W. Gordon) writes:
}
}Kermit 2.30 contains TopView detection/manipulation code.  If you run it
}as a stand-alone program under DesqView, there is no problem with it on
}either of the two systems on which I've used it.  However, if you use it
}in a DOS shell and run another DesqView-aware program in that same shell
}(at a later time), you may find out that one or more lines on the screen
}have acquired an "invisible" attribute (i.e. the line is always blank).
}There is a slight difference between TopView compatibility (Kermit) and
}DesqView compatibility.

What DESQview does is update the screen for you when you write to the virtual
screen.  TopView requires an explicit call to update the screen.  If DESQview
gets this call, it will stop implicitly updating the screen and require the
call.  Most DESQview-aware programs use the implicit screen update, since
without explicit update calls, making the program DV-aware is about ten lines
of code in the screen-address determination routine.

There is a call to turn the implicit updates back on.  I'll see about whipping
up a short program later tonight....

}
}Secondly, there are times when DesqView zero's out the Com1/2/3/4 pointers
}at 40h:0h.  Kermit makes the associated ports "unavailable."  I have not
}been able to find a specific set of sequences under which this will occur.
}I have seen it enough to know that it is not an isolated occurrence.

The ports are zero'd out as a safety measure if the program's advanced
options setup specifies that the program may be swapped out of memory.
(Wouldn't want to have an interrupt on the COM port when the program is
swapped out and some other garbage is at the interrupt handler's location,
would you?)

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