UPD78323LP datasheet(24/86 Pages) NEC

24 / 86 page

µPD78323, 78324

2.2.3

Special Function Registers (SFR)

These registers are provided with special functions. They include various peripheral hardware mode registers and control

registers (CCW).

The special function registers are assigned in the FF00H to FFFFH 256-byte space. Short direct memory addressing

is applied to the FF00H to FF1FH 32-byte area for processing with a short word length.

The bit manipulation, arithmetic and transfer instructions can be executed in all areas. The FFD0H to FFDFH 16-byte

area is externally accessible by SFR addressing. Thus, the external memory can be accessed and the external device bit

manipulation can be carried out by an instruction having a short word length.

Table 2-2 lists the special function registers (SFR). The items in the table have the following meanings.

• Symbol................. Indicates the address of the built-in special function register.

Can be described in the instruction operand column.

• R/W.......................Indicates if the corresponding special function register can read or write.

R/W : Read/write enable

: Read only enable (register bit test enable)

: Write only enable

• Manipulable bit unit

....................... Indicates the applicable operation bit unit for the corresponding special function

16-bit manipulable SFR can be described in operand sfrp. When specified by an

address, an even address is described.

1-bit manipulable SFR can be described by the bit operation instruction.

• On reset ............... Indicates the state of each register when RESET is input.

Cautions 1. Addresses for which no special function registers have been assigned cannot be accessed in the

FF00H to FFFFH area.

2. Do not write to the read only register. If data is written, the internal circuit may malfunction.

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