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MPC7400 RISC Microprocessor Users Manual
Exception Processing
17
PR
Privilege level
0 The processor can execute both user- and supervisor-level instructions.
1 The processor can only execute user-level instructions.
18
FP
Floating-point available
0 The processor prevents dispatch of oating-point instructions, including oating-point loads,
stores, and moves.
1 The processor can execute oating-point instructions and can take oating-point enabled program
exceptions.
19
ME
Machine check enable
0 Machine check exceptions are disabled.
1 Machine check exceptions are enabled.
20
FE0
IEEE oating-point exception mode 0 (see Table 4-5).
21
SE
Single-step trace enable
0 The processor executes instructions normally.
1 The processor generates a single-step trace exception upon the successful execution of every
instruction except
rT
,
isync
, and
sc
. Successful execution means that the instruction caused no
other exception.
22
BE
Branch trace enable
0 The processor executes branch instructions normally.
1 The processor generates a branch type trace exception when a branch instruction executes
successfully.
23
FE1
IEEE oating-point exception mode 1 (see Table 4-5).
24
Reserved. This bit corresponds to the AL bit of the POWER architecture.
25
IP
Exception preTx. The setting of this bit speciTes whether an exception vector offset is prepended
with Fs or 0s. In the following description,
nnnnn
is the offset of the exception.
0 Exceptions are vectored to the physical address 0x000
n_nnnn
.
1 Exceptions are vectored to the physical address 0xFFF
n_nnnn
.
26
IR
Instruction address translation
0 Instruction address translation is disabled.
1 Instruction address translation is enabled.
For more information see Chapter 5, òMemory Management.ó
27
DR
Data address translation
0 Data address translation is disabled.
1 Data address translation is enabled.
For more information see Chapter 5, òMemory Management.ó
28
Reserved.
29
PM
Performance monitor marked mode
0 Process is not a marked process.
1 Process is a marked process.
MPC7400DspeciTc; deTned as reserved by the PowerPC architecture. For more information about
the performance monitor, see Section 4.6.13, òPerformance Monitor Interrupt (0x00F00).ó
Table 4-4. MSR Bit Settings (Continued)
Bit(s)
Name
Description