HD404318 Datasheet, PDF (15/68 Pages) Hitachi Semiconductor – 4-bit HMCS400-series microcomputer

HD404318 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 (LAMR, XMRA): The memory registers (MR), which are located
in 16 addresses from $040 to $04F, are accessed with the LAMR and XMRA instructions.
10 3
03
0
WX
Y
3
0
Instruction Opcode
97
RAM address
3
0
Register Indirect Addressing
9
0
RAM address 0 0 0 1 0 0
Memory Register Addressing
1st instruction 2nd instruction
9
word
09
word
0
Instruction
Opcode
9
0
RAM address
Direct Addressing
Figure 7 RAM Addressing Modes
13