HD4043612S データシートの表示（PDF） - Renesas Electronics

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HD4043612S

4-bit HMCS400-Series microcomputer

Renesas Electronics 

HD404369 Series

Functional Description

Registers and Flags

The MCU has nine registers and two flags for CPU operations. They are shown in figure 7 and described

below.

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

Status

Initial value: 1, no R/W

Program counter

13

Initial value: 0,

no R/W

Stack pointer

Initial value: $3FF, no R/W

(PC)

9

5

1 11 1

3

0

(SPX)

3

0

(SPY)

0

(CA)

0

(ST)

0

0

(SP)

Figure 7 Registers and Flags

Accumulator (A), B Register (B): Four-bit registers used to hold the results from the arithmetic logic unit

(ALU) and transfer data between memory, I/O, and other registers.

W Register (W), X Register (X), Y Register (Y): Two-bit (W) and four-bit (X and Y) registers used for

indirect RAM addressing. The Y register is also used for D-port addressing.

14

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