NEC 78K0 Series User Manual page 92

CHAPTER 4 MEMORY BANK SELECT FUNCTION (
• Software example (to store a value to be referenced in register A)
RAMD DSEG SADDR
R_BNKA: DS 2
R_BNKN: DS 1
R_BNKRN: DS 1
;
MOV R_BNKN,#BANKNUM DATA1
MOVW R_BNKA,#DATA1
CALL !BNKRD
BNKC CSEG AT
BNKRD:
PUSH HL
MOV A,R_BNKN
XCH A,BANK
MOV R_BNKRN,A
MOVW AX,R_BNKA
XCHW HL,AX
MOV A,[HL]
XCH A,R_BNKRN
MOV BANK,A
MOV A,R_BNKRN
POP HL
RET
DATA CSEG BANK3
DATA1: DB 0AAH
END
Remark In the software example above, the X register is destructed.
92
; Secures RAM for specifying an address at the reference destination.
; Secures RAM for specifying a memory bank number at the reference destination.
; Secures RAM for saving a memory bank number at the reference source.
; Stores the memory bank number at the reference destination.
; Stores the address at the reference destination.
; Calls a subroutine for referencing between memory banks.
:
:
7000H
; Subroutine for referencing between memory banks.
; Saves the contents of register HL.
;
; Swaps the memory bank number at the reference source for that at the reference
; destination
; Saves the memory bank number at the reference source.
;
; Specifies the address at the reference destination.
; Reads the target value.
; Acquires the memory bank number at the reference source.
; Specifies the memory bank number at the reference source.
;
; Restores the contents of register HL.
; Return
Preliminary User's Manual U17260EJ3V1UD
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PD78F0536, 78F0537, AND 78F0537D ONLY)