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CHAPTER 3
CPU ARCHITECTURE
User’s Manual U12790EJ2V0UD
3.2.3 Special-function registers (SFR)
Unlike a general-purpose register, each special function register has a special function.
Special-function registers are allocated in the area FF00H to FFFFH.
Special-function registers can be manipulated like general-purpose registers, using operation, transfer, and bit
manipulation instructions. The manipulatable bit units, 1, 8 and 16, depend on the special-function register type.
Each bit manipulation unit can be specified as follows.
 1-bit manipulation
Use the symbol reserved in the assembler for the 1-bit manipulation instruction operand (sfr.bit).
This manipulation can also be specified with an address.
 8-bit manipulation
Use the symbol reserved in the assembler for the 8-bit manipulation instruction operand (sfr).
This manipulation can also be specified with an address.
 16-bit manipulation
Use the symbol reserved in the assembler for the 16-bit manipulation instruction operand (sfrp).
When addressing an address, use an even address.
Table 3-4 gives a list of special-function registers. The meanings of items in the table are as follows.
 Symbol
This is a symbol to indicate the address of the special-function register.
These symbols are reserved in the DF178098 and RA78K0, and defined by the header file sfrbit.h in the CC78K0.
They can be written as instruction operands when the RA78K0, ID78K0, ID78K0-NS, ID78K0-NS-A, or SM78K0
is used.
 R/W
Indicates whether the corresponding special-function register can be read or written.
R/W:
Read/write enabled
R:
Read only
R&Reset: Read only (reset to 0 when read)
W:
Write only
 Manipulatable bits
indicates the manipulatable bit units 1, 8, and 16. – indicates the bit units that cannot be manipulated.
 After reset
Indicates the status of each register upon reset. The values of special-function registers whose addresses are
not shown in the table are undefined after reset.