NEC 78K0 Series User Manual page 80

3.4 Operand Address Addressing
The following methods are available to specify the register and memory (addressing) to undergo manipulation
during instruction execution.
3.4.1 Implied addressing
[Function]
The register that functions as an accumulator (A and AX) among the general-purpose registers is automatically
(implicitly) addressed.
Of the 78K0/KE2 instruction words, the following instructions employ implied addressing.
Instruction
MULU A register for multiplicand and AX register for product storage
DIVUW AX register for dividend and quotient storage
ADJBA/ADJBS A register for storage of numeric values that become decimal correction targets
ROR4/ROL4 A register for storage of digit data that undergoes digit rotation
[Operand format]
Because implied addressing can be automatically determined 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.
80
CHAPTER 3 CPU ARCHITECTURE
Register to Be Specified by Implied Addressing
Preliminary User's Manual U17260EJ3V1UD