Abstract: The driver of a standard VxWorks I/O device as well as its working principle are introduced in this paper, and configuration techniques of PCI bus in real-time multitask oporating system are illustrated. Then take PCI device as example, a non-standard interface device driver is implemented by combining tasks and interrupt service. Finally, memory mapping, DMA data transfer interrupt handling and cache coherency issues in real-time operating system desigla are described in detail.