Nec PD750008 User Manual download pdf (Page 75)

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CHAPTER 4 INTERNAL CPU FUNCTIONS

Data memory is undefined when it is reset. For this reason, it is to be initialized to zero (RAM clear) usually

at the start of a program. Remember to perform this initialization. Otherwise, unexpected bugs may occur.

Example The following program clears data at addresses 000H to 1FFH in RAM.

SET1 MBE

SEL MB0

MOV XA,#00H

MOV HL,#04H

RAMC0: MOV @HL,A ; Clear 04H to FFH

Note

INCS L ; L <– L + 1

BR RAMC0

INCS H ; H <– H + 1

BR RAMC0

SEL MB1

RAMC1: MOV @HL,A ; Clear 100H to 1FFH

INCS L ; L <– L + 1

BR RAMC1

INCS H ; H <– H + 1

Note Data memory locations at 000H to 003H are allocated to general registers XA and HL, so these are

not cleared.

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Nec PD750008 User Manual Page 75

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