MB89935B 查看數據表（PDF） - Fujitsu

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MB89935B

8-bit Proprietary Microcontroller

Fujitsu 

MB89930A Series

2. Registers

The MB89930A series has two types of registers; dedicated registers in the CPU and general-purpose registers

in the memory. The following dedicated registers are provided :

Program counter (PC) :

A 16-bit register for indicating instruction storage positions

Accumulator (A) :

A 16-bit temporary register for storing arithmetic operations, etc. When the

instruction is an 8-bit data processing instruction, the lower byte is used.

Temporary accumulator (T) : A 16-bit register which performs arithmetic operations with the accumulator

When the instruction is an 8-bit data processing instruction, the lower byte is

used.

Index register (IX) :

A 16-bit register for index modification

Extra pointer (EP) :

A 16-bit pointer for indicating a memory address

Stack pointer (SP) :

A 16-bit register for indicating a stack area

Program status (PS) :

A 16-bit register for storing a register pointer, a condition code

16 bit

PC

A

: Program counter

: Accumulator

Initial value

FFFDH

Indeterminate

T

: Temporary accumulator

Indeterminate

IX

: Index register

Indeterminate

EP

: Extra pointer

Indeterminate

SP

RP

CCR

PS

: Stack pointer

: Program status

Indeterminate

I-flag = 0, IL1, 0 = 11

The other bit values are indeterminate.

The PS can further be divided into higher 8 bits for use as a register bank pointer (RP) and the lower 8 bits for

use as a condition code register (CCR) . (See the diagram below.)

• Structure of the Program Status Register

RP

CCR

bit15 bit14 bit13 bit12 bit11 bit10 bit9 bit8 bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 CCR initial value

PS R4 R3 R2 R1 R0 − − − H I IL1 IL0 N Z V C X011XXXXB

× : Undefined

H-flag

I-flag

IL1,0

N-flag

Z-flag

V-flag

C-flag

17

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