一个简单的流驱动程序，电脑与外接设备并行通信需要用驱动程序，这里是一个简单流驱动程序，希望能够给嵌入式初级编程人员带来帮助-A simple flow-driven process, computer and external devices need to use parallel communication driver, here is a simple flow-driven process, embedded primary hope to be able to help programmers