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Chapter 5
CPU Registers
1. General-purpose Registers
Registers R0 through R15 are general-purpose registers. These registers are used for accumulator and
memory access pointers on various operations.
R0
R1
...
...
R12
R13
R14
R15
Of 16 registers, the following registers are reserved for special application.
• R13: Virtual accumulator
• R14: Frame pointer
• R15: Stack pointer
Initial values by reset are indeterminate for R0 through R14. Initial value by reset is 00000000
for R15.
2. Dedicated Registers
Dedicated registers consist of program counter (PC), program status (PS), table-base register (TBR), return
pointer (RP), system stack pointer (SSP), user stack pointer (USP) and multiply & divide register (MDH/MDL).
Program counter
Program status
Table-base register
Return pointer
System stack pointer
User stack pointer
Multiply & divide register
Figure 1-1 General-purpose Registers
32 bit
...
...
AC
FP
SP
Figure 2-1 Dedicated Registers List
Chapter 5 CPU Registers
1.General-purpose Registers
[Initial value]
XXXX XXXX
H
...
...
...
...
XXXX XXXX
H
0000 0000
H
(SSP value)
H
113
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