This is a hack of id's serial device driver.  It allows arbitrary baudrate,
hardware handshaking, arbitrary irq, and arbitrary port addresses.  This will
allow you to run your V32bis modem at higher than 9600 baud.  Also, some
problems with dialing and answering the modem have been fixed (some modems
can not accept command strings at full speed).  The new structure of the
modem.cfg file is described in the accompanying modem.cfg file.

*Important: disable MNP5 compression, but leave V42bis running.  Check your
modem manual for the required init string.  With a 8250, do not lock the baud
rate higher than 19200 or doom will grind to a halt.

Many portions of the code were rewritten with optimization in mind.  Two
machines with 8250s running a null-modem and a 19200 baud rate will yield
a fast game.  The routine also provides diagnostics at the exit of doom which
indicate how many characters have been sent and how many have been received, as
well as how many TX and RX interrupts have occurred.  With a 16550, the TX and
RX FIFO utilization statistics should be around 9-11%, if not something may
be wrong with your 16550.  For anyone interested, ID had a crucial bug in their
code, they did not initialize the outque and inque pointers; this would cause
random slowdowns.

To use this fix, rename the original sersetup.exe in your doom 1.2 directory.
Copy the new file into your doom 1.2 directory, along with the sample modem.cfg.
Use as you would the normal setup.exe to launch a modem game. Play doom!

Modified from original ID code by:
Tony da Costa, U.B.C. Electrical Engineers, (cdacosta@ee.ubc.ca)
March 2, 1994

If you would like to see some other controls added to the modem.cfg file, drop
me a line at my Internet address.