4位數(shù)碼管電子時鐘（冒號為秒閃爍）

   org 0000h
   ajmp main
   org 000bh
   ljmp inti0
   org 0030h
main: mov ie,#82h
      mov tmod,#01h
   mov th0,#4ch
   mov tl0,#00h
   mov 31h,#00
   mov 32h,#00
   mov 33h,#00
   mov sp,#60h
   setb tr0
loop:lcall display
     lcall keyer
     ajmp loop
display: mov a,31h  ;秒顯示
        mov b,#10
  div ab
  mov 20h,a
  mov 21h,b
disp1:  mov a,20h  ;秒十位顯示
  mov dptr,#table
  movc a,@a+dptr
  mov p0,a
  clr p2.0
  lcall del1ms
  setb p2.0
disp2:  mov a,21h  ;秒個位顯示
        mov dptr,#table
  movc a,@a+dptr
  mov p0,a
  clr p2.1
  lcall del1ms      
  setb p2.1
disp3:  mov a,32h    ;分顯示
        mov b,#10
  div ab
  mov 22h,a
  mov 23h,b
disp4: mov a,22h     ;分十位顯示
  mov dptr,#table
  movc a,@a+dptr
  mov p0,a
  clr p2.6
  lcall del1ms
  setb p2.6   
disp5:  mov a,23h     ;分個位顯示
        mov dptr,#table
  movc a,@a+dptr
  mov p0,a
  clr p2.7
  lcall del1ms
  setb p2.7
disp6:  mov a,33h   ;時顯示
  mov b,#10
  div ab
  mov 24h,a
  mov 25h,b
disp7:  mov a,24h   ;時十位顯示
        mov dptr,#table
  movc a,@a+dptr
  mov p0,a
  clr p2.4
  lcall del1ms
  setb p2.4
disp8:  mov a,25h   ;時個位顯示
  mov dptr,#table
  movc a,@a+dptr
  mov p0,a
  clr p2.5
  lcall del1ms
  setb p2.5
  ret
inti0:push acc
    push psw
 clr ea
 mov th0,4ch
 mov tl0,#00h
 inc 3ah
 mov a,3ah
 cjne a,#40,out
 mov 3ah,#00
 cpl p2.2
 inc 31h   ;秒加1
 mov a,31h
 cjne a,#60,out
 mov 31h,#00
 inc 32h  ;分加1
 mov a,32h
 cjne a,#60,out
 mov 32h,#00
 inc 33h   ;時加1
 mov a,33h
 cjne a,#24,out
 mov 33h,#00
out:setb ea
     pop psw
  pop acc
     reti
table: db 0c0h,0f9h,0a4h,0b0h,99h,92h,82h,0f8h,80h,90h
del1ms: mov r7,#10
del1:mov r6,#50
del2:djnz r6,del2
     djnz r7,del1
  ret
del20ms:mov r5,#40
del3:mov r4,#250
del4:djnz r4,del4
     djnz r5,del3
  ret
keyer:jnb p3.2,key1  ;分加1按鈕
      jnb p3.3,key2  ;時加1按鈕
   sjmp keyout
key1:lcall del20ms
     jb p3.2,keyout
  jnb p3.2,$
  inc 32h   ;分加1
  mov a,32h
  cjne a,#60,keyout
  mov 32h,#00
  sjmp keyout
key2:lcall del20ms
     jb p3.3,keyout
  jnb p3.3,$
  inc 33h    ;時加1
  mov a,33h
  cjne a,#24,keyout
  mov 33h,#00
  sjmp keyout
keyout:ret
end