org     0
start:
        mov      a,#0
        setb     p2.0
        setb     p2.1
loop:   mov      p0,a
        jnb      p2.0,jia
        jnb      p2.1,jian
        jmp      loop
jia:    jnb      p2.0,jia          ;源程序里面加到9后面顯示亂碼，現在加進這些程序后就從0到9再加1到0
        cjne     a,#9,jiajia
        mov      a,#0
        mov      p0,a
        jmp      loop
jiajia:    inc      a
        
        ; da      a
        jmp      loop
jian:   jnb      p2.1,jian  ;教材上錯誤
        jz       bianjian
        dec      a
        jmp      loop

bianjian:   mov      a,#9
        jmp      loop
        end                             ;程序結尾要有END