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Article #1469Re: int 9h
From: Ralf Brown
Date: Sat, 12 Sep 1992 23:10
Date: Sat, 12 Sep 1992 23:10
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1555 bytes
In article <18t26lINN3jm@darkstar.UCSC.EDU> noesis@ucscb.UCSC.EDU (95016000) writes: }at the end of your interrupt you need an 'out 20h, 20h' or your machine will }lock. But only if you DON'T chain to the original INT 9 handler. The original handler will issue that OUT (it tells that interrupt controller that the highest-priority pending interrupt has been handled). If you issue it again, it is possible that a lower-priority interrupt (i.e. anything but a timer tick) which has occurred while INT 9 was being handled will be lost. For that reason, it is preferable that you issue an OUT 20h,61h instead (this says that IRQ1 has been handled). -- Internet: RALF+@CS.CMU.EDU |The University would disclaim this if it knew... FIDO: Ralf Brown 1:129/26.1 | BIT: RALF%CS.CMU.EDU@CARNEGIE|"Success has a simple formula: do your best, AT&Tnet: (412)268-3053 school| and people may like it." -- Sam Ewing
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Path: arc1-ca.pugleaf.net!sparky!uunet!sun-barr!cs.utexas.edu!sdd.hp.com!uakari.primate.wisc.edu!usenet.coe.montana.edu!news.u.washington.edu!ogicse!das-news.harvard.edu!cantaloupe.srv.cs.cmu.edu!ralf From: ralf+@cs.cmu.edu (Ralf Brown) Newsgroups: comp.os.msdos.programmer Subject: Re: int 9h Message-ID: <BuHn1n.Kwq.2@cs.cmu.edu> Date: 12 Sep 92 23:10:33 GMT Article-I.D.: cs.BuHn1n.Kwq.2 References: <DAVIS.92Sep11115609@pacific.mps.ohio-state.edu> <18t26lINN3jm@darkstar.UCSC.EDU> Sender: news@cs.cmu.edu (Usenet News System) Organization: School of Computer Science, Carnegie Mellon Lines: 17 Nntp-Posting-Host: b.gp.cs.cmu.edu