data written to the port and where to get the data read from it. Available
modes are 'null' (no input/output), 'file' (output to a file specified as
the 'dev' parameter), 'term' (serial terminal) and 'raw' (use the real serial
port - under construction for win32).
- descriptions for serial and parallel options in bochsrc sample updated
f1a0f56d55