xmem.asm

来自「51系列单片机的汇编程序包」· 汇编 代码 · 共 34 行

;=========== 外部存储器扩展实验==========
        ORG 0
JG510:  MOV DPTR,#0000H
        MOV R6,#08H
        MOV A,#55H
        CLR P1.0
RAM1:   MOV R7,#00H
RAM2:   MOVX @DPTR,A
        INC DPTR
        DJNZ R7,RAM2
        DJNZ R6,RAM1
        SETB P1.0
        MOV R6,#08H
        MOV DPTR,#0000H
RAM3:   MOV R7,#00H
RAM4:   MOVX A,@DPTR
        CJNE A,#55H,RAM6
        INC DPTR
        DJNZ R7,RAM4
        DJNZ R6,RAM3
RAM5:   CLR  P1.0
        CALL DELAY
        SETB P1.0
        CALL DELAY
        SJMP RAM5
RAM6:   CLR P1.0
        SJMP $
DELAY:  MOV R5,#00H
        MOV R4,#00H
DELAS:  DJNZ R4,$
        DJNZ R5,DELAS
        RET
        END