Most input devices used for virtual reality systems today make use of a computer's serial port for data communication. For that reason, it is important that device driver authors have at least a basic understanding of the concepts behind the VPR serial port abstraction. In our experience, serial port programming is not much different than other I/O programming. Implementing the communication protocol used by a given device tends to be the hard part, and that will likely be the case regardless of the underlying hardware.

The VPR serial port abstraction is based on the concepts implemented by the standard termios serial interface used by most modern UNIX-based operating systems [Ste92]. As such, the API allows enabling and disabling of a subset of the serial device features that can be manipulated using termios directly. To provide cross-platform semantics, however, some termios features are not included because there is no corresponding capability with Win32 overlapped I/O. Furthermore, any termios settings that relate specifically to modems are not included in the VPR serial port abstraction.