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NOTE
The processor exits BDM when a bus error or address error occurs
on the first instruction prefetch from the new PC -
the error is
trapped as a normal mode exception. The stacked value of the
current PC may not be valid in this case, depending on the state of
the machine prior to entering BDM. For address error, the PC
does not reflect the true return PC.
Instead, the stacked fault
address is the (odd) return PC.
Command Format:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
o
o
I
0
I
a
I
0
I
0
I
0
I
0
I
0
I
0
I
0
I
Command Sequence:
Operand Data:
None
Result Data:
None
7.2.8.13 Call User Code (CALL)
This instruction provides a convenient way to patch user code. The return PC is
stacked at the location pointed to by the current SP. The stacked PC serves as
a return address to be restored by the RTS command that terminates the patch
routine. After stacking is complete, the 32-bit operand data is loaded into the
PC. The pipeline is flushed and refilled from the location pointed to by the new
PC. BDM is exited, and normal mode instruction execution begins.
MOTOROLA
7-28
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CPU32 REFERENCE MANUAL
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