NEC mPD789101, User Manual

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User’s Manual U13045EJ2V0UM00
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CHAPTER 4 CPU ARCHITECTURE
4.4.6 Based addressing
[Function]
8-bit immediate data is added to the contents of the base register, that is, the HL register pair, and the sum
is used to address the memory. Addition is performed by expanding the offset data as a positive number to
16 bits. A carry from the 16th bit is ignored. This addressing can be carried out for all the memory spaces.
[Operand format]
Identifier Description
— [HL+byte]
[Description example]
MOV A, [HL+10H]; When setting byte to 10H
Instruction code 0 0 1 0 1 1 0 1
0 0 0 1 0 0 0 0
4.4.7 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
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
Instruction code 1 0 1 0 1 0 1 0