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2.8
Register Bank
A register bank consists of eight words. The register bank can be used as the following
general-purpose registers for arithmetic operations: byte registers R0 to R7, word
registers RW0 to RW7, and long word registers RL0 to RL3. In addition, the register
bank can be used as instruction pointers.
■ Register Bank
Table 2.8-1 lists the functions of the registers. Table 2.8-2 indicates the relationship between the registers.
In the same manner as for an ordinary RAM area, the register bank values are not initialized by a reset. The
status before a reset is maintained. When the power is turned on, however, the register bank will have an
undefined value.
Table 2.8-1 Register Functions
R0 to R7
RW0 to RW7
RL0 to RL3
Table 2.8-2 Relationship between Registers
Used as operands of instructions.
Note: R0 is also used as a counter for barrel shift or normalization instructions.
Used as pointers.
Used as operands of instructions.
Note: RW0 is used as a counter for string instructions.
Used as long pointers.
Used as operands of instructions.
R0
R1
R2
R3
R4
R5
R6
R7
RW0
RW1
RW2
RW3
RW4
RW5
RW6
RW7
CHAPTER 2 CPU
RL0
RL1
RL2
RL3
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