HD404328 Datasheet, PDF (74/96 Pages) Hitachi Semiconductor – 4 BIT SINGLE CHIP MICROCOMPUTER

HD404328 Series
Addressing Modes
RAM Addressing Modes
The MCU has three RAM addressing modes, as shown in figure 44 and described below.
Register Indirect Addressing Mode: The contents of the W, X, and Y registers (10 bits in total) are used
as a RAM address.
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.
Memory Register Addressing Mode: The memory registers (MR), which consist of 16 digits from $040–
$04F, are accessed with the LAMR and XMRA instructions.
W register X register
Y register
W₁ W₀ X₃ X₂ X₁ X₀ Y₃ Y₂ Y₁ Y₀
RAM address AP 9 AP 8 AP 7 AP 6 AP 5 AP 4 AP 3 AP 2 AP 1 AP 0
Register Indirect Addressing
1st word of instruction
Opcode
2nd word of instruction
d ₉ d ₈ d ₇ d ₆ d ₅ d ₄ d ₃ d ₂ d₁ d ₀
RAM address ^AP9 ^AP8 ^AP7 ^AP 6 AP 5 AP 4 AP 3 AP 2 AP 1 AP 0
Direct Addressing
Instruction
Opcode
m₃ m₂ m₁ m₀
000100
RAM address AP 9 AP 8 AP 7 AP 6 AP 5 AP 4 AP 3 AP 2 AP 1 AP 0
Memory Register Addressing
Figure 44 RAM Addressing Modes
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