Is BIOS Reentrant?

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#3008

From: Bob Davis
Date: Mon, 12 Nov 1990 19:41

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	In what I read about designing TSRs, warnings are issued
about monitoring the "InDOS" flag and/or "DOSOK" (Int28h) to determine when
DOS function calls can safely be made. The impression is usually
left on me that BIOS calls are OK without such monitorings.

	Is this true? Is BIOS reentrant?

	May I safely use ALL Interrupts below 20h without checking
	on ANY such flags or indicators in TSRs?

	Is it ONLY when I need to use Interrupts above 20h that the
	tedious checks to avoid re-entering DOS are necessary?

Thanks.
 
______________________________________________________________________________
Bob Davis, UofALA'66   \\ INTERNET : sonny@trantor.harris-atd.com  |  _   _  |
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!bu.edu!shelby!mcnc!uvaarpa!haven!uflorida!mlb.semi.harris.com!trantor.harris-atd.com!charybdis!sonny
From: sonny@charybdis.harris-atd.com (Bob Davis)
Newsgroups: comp.os.msdos.programmer
Subject: Is BIOS Reentrant?
Message-ID: <4844@trantor.harris-atd.com>
Date: 12 Nov 90 19:41:48 GMT
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