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5.4.9 Based indexed addressing
[Function]
The B or C register contents specified in an instruction are added to the contents of the base register, that is, the
HL register pair, and the sum is used to address the memory. The HL, B, and C registers to be accessed are registers
in the register bank specified with the register bank select flag (RBS0 and RBS1). The contents of the B or C register
as a positive number are expanded to 16 bits to be added. A carry from the 16th bit is ignored. This addressing
can be carried out for all the memory spaces.
[Operand format]
[Description example]
In the case of MOV A, [HL + B]
5.4.10 Stack addressing
[Function]
The stack area is indirectly addressed with the stack pointer (SP) contents.
This addressing method is automatically employed when the PUSH, POP, subroutine call and RETURN
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instructions are executed or the register is saved/reset upon generation of an interrupt request.
Stack addressing enables to address the internal high-speed RAM area only.
[Description example]
In the case of PUSH DE
128
CHAPTER 5 CPU ARCHITECTURE
Identifier
—
[HL + B], [HL + C]
Instruction code 1
0
1
0
Instruction code 1
0
1
1
Description
1
0
1
1
0
1
0
1
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