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 cont