Bus Error (Mc68010) - Motorola M68000 User Manual

protect memory contents from erroneous accesses. Only an external reset operation can
restart a halted processor.
15
LOWER ADDRESS
ACCESS ADDRESS
PROGRAM COUNTER
R/W (Read/Write): Write=0, Read=1. I/N (Instruction/Not): Instruction=0, Not=1
Figure 6-7. Supervisor Stack Order for Bus or Address Error Exception
6.3.9.2 BUS ERROR (MC68010). Exception processing for a bus error follows a slightly
different sequence than the sequence for group 1 and 2 exceptions. In addition to the four
steps executed during exception processing for all other exceptions, 22 words of
additional information are placed on the stack. This additional information describes the
internal state of the processor at the time of the bus error and is reloaded by the RTE
instruction to continue the instruction that caused the error. Figure 6-8 shows the order of
the stacked information.
MOTOROLA M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL
Freescale Semiconductor, Inc.
14 13 12 11 10
For More Information On This Product,
Go to: www.freescale.com
9 8 7 6 5
HIGH
LOW
INSTRUCTION REGISTER
STATUS REGISTER
HIGH
LOW
4 3 2 1 0
R/W I/N FUNCTION CODE
6- 17