Section 2 CPU
Rev. 3.00 Sep. 27, 2007 Page 21 of 758
REJ09B0243-0300
2.2.3 System
Registers
There are four 32-bit system registers, designated two multiply and accumulate registers (MACH
and MACL), a procedure register (PR), and program counter (PC).
•
Multiply and accumulate registers (MACH and MACL)
This register stores the results of multiplication and multiply-and-accumulate operation.
•
Procedure register (PR)
This register stores the return-destination address from subroutine procedures.
•
Program counter (PC)
The PC indicates the point which is four bytes (two instructions) after the current execution
instruction.
2.2.4
Initial Values of Registers
Table 2.1 lists the initial values of registers after a reset.
Table 2.1
Initial Values of Registers
Type of register
Register
Default
General register
R0 to R14
Undefined
R15 (SP)
SP value set in the exception handling vector table
Control register
SR
I3 to I0: 1111 (H'F)
Reserved bits: 0
Other bits: Undefined
GBR
Undefined
VBR
H'00000000
System register
MACH, MACL, PR
Undefined
PC
PC value set in the exception handling vector table
Summary of Contents for SH7124 R5F7124
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