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CHAPTER 3 CPU
■ Register Bank
A register bank can be used as general-purpose registers (byte registers R0 to R7, word registers RW0 to
RW7, long-word registers RL0 to RL3) for various arithmetic operations and pointers. A long-word
register can be used as a linear pointer that directly accesses the entire memory space.
The contents of the register bank, like ordinary RAM, are not initialized by a reset. The status before a
reset is retained. At power-on, however, the contents are undefined. Table 3.8-1lists the typical functions
of general-purpose registers.
Table 3.8-1 Typical Functions of General-purpose Registers
Register name
R0 to R7
RW0 to RW7
RL0 to RL3
56
Used as an operand in various instructions
(Note)
R0 is also used as a barrel shift counter and an instruction normalization counter
Used as a pointer
Used as an operand in various instructions
(Note)
RW0 is used also as a string instruction counter
Used as a long pointer
Used as an operand in various instructions
Function
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