NEC 78K0 Series User Manual page 87

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 of the memory spaces. However, before addressing a memory bank
that is not set by the memory bank select register (BANK), change the setting of the memory bank by using
BANK.
[Operand format]
Identifier
[Description example]
MOV A, [HL +B]; when selecting B register
[Illustration]
HL
The contents of the memory
addressed are transferred.
A
CHAPTER 3 CPU ARCHITECTURE
−
[HL + B], [HL + C]
Operation code
16
H
7
Preliminary User's Manual U17260EJ3V1UD
Description
1 0 1 0 1 0 1 1
8 7
L
+
7
B
7 Memory
0
0
0
0
87