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From: uace0@uhnix2.uh.edu (Michael B. Vederman)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: Spurious interrupt
Message-ID: <1166@uhnix2.uh.edu>
Date: 19 Aug 90 14:58:46 GMT
References: <883@ehviea.ine.philips.nl>
Reply-To: uace0@uhnix2.UUCP
Organization: University of Houston
Lines: 21

Leo -

Just as a guess, sounds like your interrupt is ocurring at the same time you
are attempting to change it.  Just some observations:

1) Be certain your interrupt is restoring any registers it destroys
2) Be certain _not_ to save registers onto the stack, but rather use a static
   storage area
3) If neither one of those help, try masking off interrupts by raising your
   ipl to 7 before issuing the xbtimer() call.  From what I can see of the
   xbtimer() call, it does not touch the ipl when it is initing the mfp, so
   you can conceivably be interrupting when you are changing.  Altho, the
   xbtimer() call does disable the interrupt before changing it...

- mike

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