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CHAPTER 5 CPU SOFTWARE ARCHITECTURE
5.1 Types of Addressing Modes
The F
2
MC-8FX CPU has the following ten addressing modes:
• Direct addressing (dir)
• Extended addressing (ext)
• Bit direct addressing (dir:b)
• Indexed addressing (@IX+off)
• Pointer addressing (@EP)
• General-purpose register addressing (Ri)
• Immediate addressing (#imm)
• Vector addressing (#k)
• Relative addressing (rel)
• Inherent addressing
■ Direct Addressing (dir)
This addressing mode, indicated as "dir" in the instruction list, is used to access the direct area from 0000
H
to 047F
H
. In this addressing, when the operand address is 00
H
to 7F
H
, it accesses 0000
H
to 007F
H
.
Moreover, when the operand address is 80
H
to FF
H
, the access is good to 0080
H
to 047F
H
at the mapping
by direct bank pointer DP setting.
■ Extended Addressing (ext)
This addressing mode, indicated as "ext" in the instruction list, is used to access the entire 64-Kbyte area. In
this addressing mode, the upper byte is specified by the first operand and the lower byte by the second
operand.
■ Bit Direct Addressing (dir:b)
This addressing mode, indicated as "dir:b" in the instruction list, is used for bit-by-bit access of the direct
area from 0000
H
to 047F
H
. In this addressing, when the operand address is 00
H
to 7F
H
, it accesses 0000
H
to 007F
H
. Moreover, when the operand address is 80
H
to FF
H
, the access is good to 0080
H
to 047F
H
at the
mapping by direct bank pointer DP setting. The position of the bit in the specified address is specified by
the value for the instruction code of three subordinate position bits.
[Example]
MOV 92H,A
0112
H
45
H
45
H
A001
B
DP
SETB 34H: 2
0034
H
XXXXX1XXB
76543 210
[Example]
XXX
B
DP