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CHAPTER 3 CPU ARCHITECTURE
3.2.3 Special function registers (SFRs)
Unlike the general registers, these registers have special functions.
They are allocated in the FF00H to FFFFH area.
The special-function registers can be manipulated like the general registers, with the operation, transfer and bit
manipulation instructions. The bit units (1, 8, or 16 bits) for the manipulation vary for each register.
Each manipulation bit unit can be specified as follows.
• 1-bit manipulation
Describe the symbol reserved with assembler for the 1-bit manipulation instruction operand (sfr.bit).
This manipulation can also be specified with an address.
• 8-bit manipulation
Describe the symbol reserved with assembler for the 8-bit manipulation instruction operand (sfr).
This manipulation can also be specified with an address.
• 16-bit manipulation
Describe the symbol reserved with assembler for the 16-bit manipulation instruction operand (sfrp).
When addressing an address, describe an even address.
Table 3-5 gives a list of special-function registers. The meaning of items in the table is as follows.
• Symbol
Symbol indicating the address of a special function register. It is a reserved word in the RA78K/0, and is defined
via the header file “sfrbit.h” in the CC78K/0. It can be described as an instruction operand when the RA78K/
0 and ID78K0 are used.
• R/W
Indicates whether the corresponding special-function register can be read or written.
R/W : Read/write enable
R
: Read only
W
: Write only
• Manipulatable bit units
Indicates the manipulatable bit unit (1, 8, or 16). “—” indicates a bit unit for which manipulation is not possible.
• After reset
Indicates each register status upon RESET input.
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