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24小时单片机汇编程序

89C51单片机数码管循环显示24小时。
org 0000h
ljmp start
org 0030h
start: mov dptr,#tab
mov 30h,#0
mov 31h,#0
mov r3,#24
mov r4,#59
mov r5,#220
lop: mov a,31h
mov b,#10
div ab
mov p2,#11110111b
movc a,@a+dptr
mov p0,a
lcall delay
mov p2,#11111011b
mov a,b
movc a,@a+dptr
mov p0,a
lcall delay

mov a,30h
mov b,#10
div ab
mov p2,#11111101b
movc a,@a+dptr
mov p0,a
lcall delay
mov p2,#11111110b
mov a,b
movc a,@a+dptr
mov p0,a
lcall delay
sjmp lop
delay: mov r7,#200
abc: mov r6,#10
djnz r6,$
djnz r7,abc
djnz r5,back
mov r5,#220
inc 30h
djnz r4,back
inc 31h
mov 30h,#0
mov r4,#59
djnz r3,back
mov 30h,#0
mov 31h,#0
back: ret
tab: db 3fh,06h,5bh,4fh,66h,6dh,7dh,07h,7fh,6fh
end