程序功能为扩展两个外部并口，两个并行端口没有确切的端口地址，通过两个并口连接两位共阳数码管，实现两位数码管的静态显示，显示数字顺序为：00~-Program features for the expansion of two external parallel port, two parallel ports do not have the exact port addresses two common anode connection via two parallel digital control to achieve two digital static display, showing numerical order as follows: 00 to 99