I'm trying to rediscover how to control the RS232 UART every PC has two of. This powerful interface could be more useful, particularly for process control or robotics. I'm not looking for a driver, unless it is highly versatile. In the original PCs one simply input or output to the UART BIOS address and the bit field was yours. The DOS driver for the COM ports began the process of hiding control by adding a new layer. Pascal and C can be used to build drivers, such as the terminal driver or modem driver. I am hoping someone in this group has some experience with this in Unix (Linux). I've reinvented the wheel plenty of times.