MPC555
/
MPC556
CENTRAL PROCESSING UNIT
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
3-20
3.9 PowerPC OEA Register Set
The PowerPC operating environment architecture (OEA) includes a number of SPRs
and other registers that are accessible only by supervisor-level instructions. Some
SPRs are RCPU-specific; some RCPU SPRs may not be implemented in other Pow-
erPC processors, or may not be implemented in the same way.
3.9.1 Machine State Register (MSR)
The machine state register is a 32-bit register that defines the state of the processor.
When an exception occurs, the current contents of the MSR are loaded into SRR1,
and the MSR is updated to reflect the exception-processing machine state. The MSR
can also be modified by the
mtmsr
,
sc
, and
rfi
instructions. It can be read by the
mfm-
sr
instruction.
shows the bit definitions for the MSR.
MSR
— Machine State Register
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
RESERVED
POW
0
ILE
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
LSB
31
EE
PR
FP
ME
FE0
SE
BE
FE1
0
IP
IR
DR
RE-
SERVED
DC-
MPEN
2
2. This bit is only available on the MPC556.
RI
LE
RESET:
0
0
0
U
0
0
0
0
0
ID1
1
NOTES:
1. Reset value of this bit depends on the value of the internal data bus line during reset.
0
0
0
0
0
0
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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