Path: utzoo!attcan!uunet!snorkelwacker!mit-eddie!bu.edu!dartvax!eleazar.dartmouth.edu!sean
From: sean@eleazar.dartmouth.edu (Sean P. Nolan)
Newsgroups: comp.sys.mac.programmer
Subject: "Spurious Interrupt..." Problem
Message-ID: <23389@dartvax.Dartmouth.EDU>
Date: 27 Jul 90 04:28:11 GMT
Sender: news@dartvax.Dartmouth.EDU
Organization: Dartmouth College, Hanover, NH
Lines: 34

Hi there...

I'm working on a project that uses a VBL task. The task is locked in the 
System Heap and VInstall'ed at INIT time. It is pretty benign, doing some 
floating-point calculations and then dropping out. It restores all its 
registers, and doesn't use any nasty memory-moving calls. (The Floating-
Point calls are via the _FP68K trap).

The task runs without a hitch on my SE running 6.0.5 system software. 
However, when I tried it on my girlfriend's SE/30 running 6.0.5, I ran into
trouble. It works ok (and calculates its values appropriately) for a short
while, usually about 4-5 minutes. Then, I drop into the debugger with a
"Spurious Interrupt or Unimplemented Interrupt Vector" message (equivalent
to System Error 11). This does NOT happen within my code, it happens always
within Dequeue or Date2Secs, and always during an FMOVE op. 

It's definitely something my task is doing, since the problem disappears
when the task is removed. But I can't figure it out for the life of me.
The only thing I can find anywhere is a note in IM II saying that the
Floating Point package does not preserve the state of the status register.
Should this matter? The register is saved and restored around my task, so it
should be ok, at least I think it should be.

Help! If anyone has run into a similar problem, please let me know. Thanks
for any help.

--- Sean

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| Sean P. Nolan     |   Net: Sean_Nolan@Dartmouth.EDU   | "That's not a      |
| Dartmouth College |                                   |  baby, that's a    |
| Hinman Box 2658   |            SCALP 'EM!             |  Mr. Potatohead!"  |
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