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From: mathrich@mthvax.cs.miami.edu (Rich Winkel)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: NMI Breakout (was: Parity error handling under DOS?)
Message-ID: <1990Aug13.212916.1485@mthvax.cs.miami.edu>
Date: 13 Aug 90 21:29:16 GMT
References: <9008101543.aa18551@PARIS.ICS.UCI.EDU> <1260@gold.GVG.TEK.COM> <1990Aug11.033457.12369@maytag.waterloo.edu>
Organization: U of Miami Dept. of Math. and Computer Science, Coral Gables, FL 33124
Lines: 11

In <1990Aug11.033457.12369@maytag.waterloo.edu> dmurdoch@watstat.uwaterloo.ca (Duncan Murdoch) writes:
>Now, for my question:  The current issue of PC Techniques (a new programming
>mag, generally pretty good) gives instructions (p. 8) to build a simple
>breakout switch, that triggers a NMI by temporarily grounding bus pin A1.
>I did it, but get no sign of anything happening, whether NMI is enabled or
>not.  (This on a no-name 8086 clone.)  
>Can anyone suggest a fix?  What do I need to do to get an NMI?
You may need to drive it negative.  Try hooking it through a resister to
a -5V line.  On the XT bus, pin B5 is at -5V.  A 1K resister should do.

Rich