Based Indexed Addressing; Stack Addressing - NEC 78K0/KD1 Series User Manual

3.4.8 Based indexed addressing

[Function]
The B or C register contents specified in an instruction word are added to the contents of the base register, that
is, the HL register pair in the register bank specified by the register bank select flag (RBS0 and RBS1), and the
sum is used to address the memory. Addition is performed by expanding the B or C register contents 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 example]
In the case of MOV A, [HL + B]

3.4.9 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.
With stack addressing, only the internal high-speed RAM area can be accessed.
[Description example]
In the case of PUSH DE
CHAPTER 3 CPU ARCHITECTURE
−
[HL + B], [HL + C]
Operation code
Operation code
Preliminary User's Manual U16315EJ1V0UD
Description
1 0 1 0 1 0 1 1
1 0 1 1 0 1 0 1
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