ORG 0000H
S1 EQU 24H
S2 EQU 25H
s3 equ 26h
s4 equ 27h
sec EQU 28h
min EQU 29H
ljmp main
main:mov sec,#0
     mov min,#0
     mov tmod,#01h
     mov tl0,#0b0h
     mov th0,#4ch
     setb tr0
sss:mov a,sec
    cjne a,#60,ccc  
    mov sec,#0
    inc min
mmm:
    mov a,min
    cjne a,#60,ccc  
    mov min,#0
    ljmp sss
ccc:
    mov r0,#20
loop:lcall aaa
   jbc tf0,setd
   sjmp loop
setd:
   mov tl0,#0b0h
   mov th0,#4ch
   djnz r0,loop
   jb p3.5,bbb
   ACALL DELAY10
   JB P3.5,setd
   JNB P3.5,$
   INC min
   ljmp mmm
bbb:INC sec
   ljmp sss
aaa:
MOV B,#10
MOV A,sec
DIV AB
MOV S1,B
MOV S2,A
MOV B,#10
MOV A,min
DIV AB
MOV S3,B
MOV S4,A
mov dptr,#tab
MOV A,S1
MOVC A,@A+DPTR
MOV P1,A
CLR P0.0
NOP
SETB P0.0
MOV A,S2
MOVC A,@A+DPTR
MOV P1,A
CLR P0.1
NOP
SETB P0.1
MOV A,S3
MOVC A,@A+DPTR
MOV P1,A
CLR P0.2
NOP
SETB P0.2
MOV A,S4
MOVC A,@A+DPTR
MOV P1,A
CLR P0.3
NOP
SETB P0.3
ret
DELAY10: MOV R4,#10
D2:MOV R5,#248
DJNZ R5,$
DJNZ R4,D2
RET
tab: db 0a0h,0bbh,62h,2ah,39h,2ch,24h,0bah,20h,28h
END