NEC 78K0 Series User Manual page 91

CHAPTER 4 MEMORY BANK SELECT FUNCTION (
4.3 Selecting Memory Bank
The memory bank selected by the memory bank select register (BANK) is reflected on the bank area and can be
addressed. Therefore, to access a memory bank different from the one currently selected, that memory bank must be
selected by using the BANK register.
The value of the BANK register must not be changed in the bank area (8000H to BFFFH). Therefore, to change
the memory bank, branch an instruction to the common area (0000H to 7FFFH) and change the value of the BANK
register in that area.
Cautions 1. Instructions cannot be fetched between different memory banks.
2. Branching and accessing cannot be directly executed between different memory banks.
Execute branching or accessing between different memory banks via the common area.
3. Allocate interrupt servicing in the common area.
4. An instruction that extends from 7FFFH to 8000H can only be executed in memory bank 0.
4.3.1 Referencing values between memory banks
Values cannot be directly referenced from one memory bank to another.
To access another memory bank from one memory bank, branch once to the common area (0000H to 7FFFH),
change the setting of the BANK register there, and then reference a value.
Bank
area
Common
area
Bank
area
Common
area
µ
PD78F0536, 78F0537, AND 78F0537D ONLY)
Memory bank m
Referencing value
Memory bank m
Preliminary User's Manual U17260EJ3V1UD
Memory bank n
Memory bank n
Referencing value
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