HD404394 データシートの表示（PDF） - Hitachi -> Renesas Electronics

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HD404394

4-bit microcomputers

Hitachi -> Renesas Electronics 

HD404344R Series/HD404394 Series

Functional Description

Registers and Flags

The CPU has nine registers and two flags. Their configurations are shown in figure 7 and explained as

follows.

Accumulator

Initial value: Undefined, R/W

3

0

(A)

B register

W register

X register

Y register

Initial value: Undefined, R/W

Initial value: Undefined, R/W

Initial value: Undefined, R/W

Initial value: Undefined, R/W

3

0

(B)

10

(W)

3

0

(X)

3

0

(Y)

SPX register

Initial value: Undefined, R/W

SPY register

Initial value: Undefined, R/W

Carry

Initial value: Undefined, R/W

3

0

(SPX)

3

0

(SPY)

0

(CA)

0

Status

Initial value: 1, no R/W

(ST)

Program counter

13

Initial value: 0,

no R/W

Stack pointer

Initial value: $3FF, no R/W

0

(PC)

9

5

0

1 11 1

(SP)

Figure 7 Registers and Flags

21

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