HD4048412 データシートの表示（PDF） - Renesas Electronics

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HD4048412

4-Bit Single-Chip Microcomputer

Renesas Electronics 

HD404849 Series

Addressing Modes

RAM Addressing Modes

The MCU has three RAM addressing modes, as shown in figure 91 and described below.

W register X register

Y register

W1 W0 X3 X2 X1 X0 Y3 Y2 Y1 Y0

RAM address AP9 AP8 AP7 AP6 AP5 AP4 AP3 AP2 AP1 AP0

Register Indirect Addressing

1st word of Instruction

Opcode

2nd word of Instruction

d 9 d 8 d7 d6 d 5 d 4 d3 d2 d1 d0

RAM address AP9 AP8 AP7 AP6 AP5 AP4 AP3 AP2 AP1 AP0

Direct Addressing

Instruction

Opcode

m3 m2 m1 m 0

000100

RAM address AP9 AP8 AP7 AP6 AP5 AP4 AP3 AP2 AP1 AP0

Memory Register Addressing

Figure 91 RAM Addressing Modes

Register Indirect Addressing Mode: The contents of the W, X, and Y registers (10 bits in total) are used

as a RAM address. When the area from $090 to $25F is used, a bank must be selected by the bank register

(V: $03F).

Direct Addressing Mode: A direct addressing instruction consists of two words. The first word contains

the opcode, and the contents of the second word (10 bits) are used as a RAM address.

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