
CHAPTER 3 CP0 REGISTERS
User’s Manual U14272EJ3V0UM
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Figure 3-16. EPC Register (When MIPS16 ISA Is Enabled)
1
(a) 32-bit mode
0
31
EPC
EIM
EPC:
Bits 31 to 1 of restart address (virtual) after exception processing.
EIM:
ISA mode at which an exception occurs (1
→
When MIPS16 SIA instruction is executed, 0
→
When MIPS III ISA instruction is executed).
1
(b) 64-bit mode
0
63
EPC
EIM
EPC:
Bits 63 to 1 of restart address (virtual) after exception processing.
EIM:
ISA mode at which an exception occurs (1
→
When MIPS16 SIA instruction is executed, 0
→
When MIPS III ISA instruction is executed).
3.2.14 Processor Revision Identifier (PRId) register (15)
The 32-bit, read-only Processor Revision Identifier (PRId) register contains information identifying the
implementation and revision level of the CPU and CP0.
Figure 3-17. PRId Register
31
16 15
8
7
0
0
Imp
Rev
Imp:
CPU core processor ID number (0x0C for the V
R
4181)
Rev:
CPU core processor revision number
0:
Reserved for future use. Write 0 in a write operation. When this field is read, 0 is read.
The processor revision number is stored as a value in the form y.x, where y is a major revision number in bits 7 to
4 and x is a minor revision number in bits 3 to 0.
The processor revision number can distinguish CPU core revisions of the V
R
4181, however there is no guarantee
that changes to the CPU core will necessarily be reflected in the PRId register, or that changes to the revision
number necessarily reflect real CPU core changes. Therefore, create a program that does not depend on the
processor revision number field.