M38263EBFS datasheet(70/91 Pages) RENESAS

Nome de Peças	M38263EBFS

Descrição Electrónicos	SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

PDF	91 Pages

Scroll/Zoom	100%

Fabricante Electrônico	RENESAS [Renesas Technology Corp]

Página de início	http://www.renesas.com

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70 / 91 page

Rev.1.00

Sep 06, 2006

page 70 of 88

REJ03B0181-0100

3826 Group (One Time PROM version)

Fig. 3.3.1 Initialization of processor status register

➁ How to reference the processor status register

To reference the contents of the processor status register (PS), execute the PHP instruction

once then read the contents of (S+1). If necessary, execute the PLP instruction to return the

PS to its original status.

3.3 Notes on use

3.3.1 Notes on programming

(1)

Processor status register

➀ Initializing of processor status register

Flags which affect program execution must be initialized after a reset.

In particular, it is essential to initialize the T and D flags because they have an important effect

on calculations.

● Reason

After a reset, the contents of the processor status register (PS) are undefined except for the

I flag which is “1”.

Fig. 3.3.3 Stack memory contents after PHP

instruction execution

Reset

↓

Initializing of flags

↓

Main program

(S)

(S)+1

Stored PS

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