Path: utzoo!attcan!uunet!ncrlnk!ncr-sd!hp-sdd!hplabs!ucbvax!TAURUS.BITNET!zifrony
From: zifrony@TAURUS.BITNET
Newsgroups: comp.sys.ibm.pc
Subject: Re: Dos calls within TSR's
Message-ID: <897@taurus.BITNET>
Date: 16 Nov 88 17:24:03 GMT
References: <17309@vax5.CIT.CORNELL.EDU>
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: zifrony%virgo.UUCP@CUNYVM.CUNY.EDU (Zifrony Doron)
Organization: Tel-Aviv Univesity Math and CS school, Israel
Lines: 15

It seems DOS itself is not re-entrant.  That means that calling a DOS
routine from within DOS is a no-no.  Your interrupt routine, which attempts
to call DOS, may be interrupting DOS itself, and that's ashame.

I have heard of an undocumented interrupt (at least in DOS 3.30), which
enables the user to know whether its interrupt routine interrupted
a DOS service or not.  I think books dealing with TSRs mention this
function.

Sorry, I don't recall the name of any of these books.

Doron Zifrony    -  zifrony@taurus.bitnet or zifrony@Math.Tau.Ac.IL
Msc student
Tel Aviv Univ.
Israel