NEC PD75402A, PD75P402 user manual Peripheral hardware area, Mov

CHAPTER 4. INTERNAL CPU FUNCTIONS

(2) Peripheral hardware area

The peripheral hardware area is mapped to memory bank 15’s addresses F80H to FFFH.

The operation is performed by the memory manipulation instruction just as in the static RAM. In the peripheral hardware, however, the operable bit unit differs from one address to another. It is impossible to access an address to which the peripheral hardware is not assigned since the data memory is not built in. (See Table 3-4 “μPD75402A I/O Map".)

Note The static RAM is indefinite at reset. Therefore, it should be initialized to zero at the beginning of the

program (RAM clear). This must be carried out for sure to avoid unexpected bugs.

Example Clear all the areas (00H to 3FH) of the static RAM (FFH remains in the HL register, however).

	MOV	HL, #3FH
	MOV	A, #0H
LOOP:	MOV	@HL, A: Clear (0) 00H to 3FH
	DECS	L
	BR	LOOP
	DECS	H
	BR	LOOP

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