HD4074344 Datasheet, PDF (82/100 Pages) Hitachi Semiconductor – 4-bit microcomputers

HD404344R Series/HD404394 Series
Addressing Modes
RAM Addressing Modes
Register Indirect Addressing Mode: The contents of the W, X, and Y registers (10 bits 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 are located in 16 digits from
$040 to $04F, are accessed with the LAMR and XMRA instructions.
ROM Addressing Modes
Direct Addressing Mode: A program can branch to any address in ROM memory space by executing the
JMPL, BRL, or CALL instruction.
10 3 0 3 0
WX
Y
30
Instruction Opcode
97
RAM address
30
Register Indirect Addressing
9
0
RAM address 0 0 0 1 0 0
Memory Register Addressing
1st instruction 2nd instruction
9 word
0 9 word
0
Instruction
Opcode
9
0
RAM address
Direct Addressing
Figure 62 RAM Addressing Modes
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