Under DOS,lower-level driver is implemented by residential interruptting program, while under UNIX, it is implemented by UNIX STREAMS. The data receiving in both drivers employs hardware interruption so as to prevent the leakage of characters effectively.

• DOS下的底层驱动程序用驻留中断实现，UNIX下的驱动程序用UNIX的流机制实现，数据接收均采用硬件中断，有效地防止了漏字符现象的发生。