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From: jlehmann@wpi.WPI.EDU (Jonas A. Lehmann)
Newsgroups: comp.sys.m68k
Subject: $$$ HELP: Multiple Exception Handling on MC68008 System
Message-ID: <1990Nov16.045849.2972@wpi.WPI.EDU>
Date: 16 Nov 90 04:58:49 GMT
References: <16871@samsung.samsung.com> <1990Nov9.214237.28116@athena.mit.edu>
Organization: Worcester Polytechnic Institute
Lines: 26

Hi,
We are currently developing a debugger for embedded systems running on a 
PC-AT with the embedded system being a MC68008 based machine.


Our problem is trying to implement single stepping.
We have, or seem to have, no problems single stepping over normal
instructions but

WHAT HAPPENS IF...

Trace-Bit is set and we begin executing. The instruction that follows causes
a DIVIDE BY ZERO EXCEPTION. What specifically happens with the order in which
these exceptions are processed and what happens with the PC,SR? 
We Assume the Exception Handling routines just do an RTE.
Also, if one exception is pending during another what is the easiest way
to check this and to determine which one is pending?


Please email any info to 

Jonas Lehmann - jlehmann@wpi.wpi.edu
Jeff Kohler   - jkohler@wpi.wpi.edu


Thank you ...