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Exception Processing
8-2
M68060 USER’S MANUAL
MOTOROLA
number. For all other exceptions, internal logic provides the vector number. This vector num-
ber is used in the last step to calculate the address of the exception vector. Throughout this
section, vector numbers are given in decimal notation.
Figure 8-1. General Exception Processing Flowchart
EXIT
DETERMINE VECTOR
NUMBER
(DOUBLE BUS FAULT)
CALCULATE
ADDRESS OF FIRST
INSTRUCTION OF
EXCEPTION HANDLER
EXIT
(DOUBLE BUS FAULT)
ENTRY
SAVE CONTENTS
TO STACK FRAME
(SEE NOTE)
FETCH FIRST
INSTRUCTION OF
EXCEPTION HANDLER
OTHERWISE
BEGIN EXECUTION
OF EXCEPTION
HANDLER
BUS ERROR
BUS ERROR OR
ADDRESS ERROR
IF PROCESSING AN
ACCESS ERROR EXCEPTION
BUS ERROR OR
ADDRESS ERROR
IF NOT PROCESSING AN
ACCESS ERROR EXCEPTION
S 1
T 0
VECTOR = 2
HALTED STATE
PST4–PST0 = $1C
OTHERWISE
SAVE INTERNAL
COPY OF SR
S 1
T 0
(SEE NOTE)
NOTE: THESE BLOCKS VARY FOR RESET AND INTERRUPT EXCEPTIONS.
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