200548601.txt

1 任务 模拟抢答器工作：抢答开始后

           DB   39H,5EH,79H,71H     ;"C","D","E","F"
抢答器程序
ORG     00H
LJMP   START
ORG   50H
START:
MOV   TMOD,#20H
MOV   TL1,#0FDH
MOV   TH1,#0FDH
SETB   TR1
MOV   SCON,#50H
MOV    PCON,#80H
SETB  EA
SETB   ES
MAIN:
JNB   P1.0,YI
JNB   P1.1,ER
JNB   P3.2,SAN
JNB   P3.3,SI
LJMP   MAIN
YI:
MOV  A,#1
LCALL  FASONG
LJMP   MAIN
ER:
MOV   A,#2
LCALL  FASONG
LJMP  MAIN
SAN:
MOV   A,#3
LCALL  FASONG
LJMP  MAIN
SI:
MOV   A,#4
LCALL  FASONG
LJMP   MAIN
FMQ:
CLR P3.4
LCALL  DL1
SETB   P3.4
RET
FASONG:
MOV   SBUF,A
JNB   TI,$
CLR   TI
LCALL  XIANSHI
RET
XIANSHI:
MOV  DPTR,#TAB
MOVC   A,@A+DPTR
MOV   P2,A
LCALL  FMQ
LCALL  DL
LCALL  DL
MOV   P2,#11111111B
RET
ORG     200H
TAB:   DB    10000001B,11111001B,01000011B,01010001B,00111001B
DL : MOV R5,10
D1:  MOV R6,#20
D2:  MOV R7,20                                    
D3:DJNZ R7,D3     
   DJNZ R6,D2      
DJNZ R5,D1   
    RET
DL1:     MOV     20H,#0FFH
DELAY:MOV     21H,#0FFH
AGAIN:NOP
      NOP
      DJNZ    21H,AGAIN
      DJNZ    20H,DELAY
       RET