Operand Address Addressing; Implied Addressing - NEC PD78081(A) User Manual

3.4 Operand Address Addressing

The following various methods are available to specify the register and memory (addressing) which undergo
manipulation during instruction execution.

3.4.1 Implied addressing

[Function]
The register which functions as an accumulator (A and AX) in the general register is automatically (illicitly)
addressed.
Of the PD78083 Subseries instruction words, the following instructions employ implied addressing.
Instruction
MULU
DIVUW
ADJBA/ADJBS
ROR4/ROL4
[Operand format]
Because implied addressing can be automatically employed with an instruction, no particular operand format is
necessary.
[Description example]
In the case of MULU X
With an 8-bit 8-bit multiply instruction, the product of A register and X register is stored in AX. In this example,
the A and AX registers are specified by implied addressing.
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CHAPTER 3 CPU ARCHITECTURE
Register to be Specified by Implied Addressing
A register for multiplicand and AX register for product storage
AX register for dividend and quotient storage
A register for storage of numeric values which become decimal correction targets
A register for storage of digit data which undergoes digit rotation