Based Addressing; Based Indexed Addressing - NEC 78K/0 Series User Manual

3.2.7 Based addressing

[Function]
8-bit immediate data is added to the contents of the HL register pair as a base register and the sum is used
to address the memory. The HL register pair to be accessed is in the register bank specified by the register
bank select flag (RBS0 and RBS1). 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
—
[HL+byte]
[Description example]
MOV A, [HL+10H]; When setting byte to 10H

3.2.8 Based indexed addressing

[Function]
The B or C register contents specified in an instruction word are added to the contents of the HL register
pair as a base register 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 by the register bank select flag (RBS0 to RBS1). Addition is
performed by expanding the B or C register 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
—
[HL+B], [HL+C]
[Description example]
In the case of MOV A, [HL+B]
30
CHAPTER 3 ADDRESSING
Description
Instruction code 1 0
0 0
Description
Instruction code 1 0
User's Manual U12326EJ4V0UM
1 0 1 1 1 0
0 1 0 0 0 0
1 0 1 0 1 1