The 'userial' code set sends commands designed for the DS2480
'Universal Serial 1-Wire Line Driver Master chip'.  It can
be made to work on any serial port that can do 9600, N, 8, 1.
The following is a description of the API needed to port this
code set to any platform.  See the 'TODO.C' file in the
directory '\source\lib\userial'.

Required API that must be implemented for the 'userial' code
set to function:

   ReadCOM  
         Read a specified number of bytes from the serial COM port.
         This API must timeout if the specified number of bytes
         have not arrived.  The timeout is dependent on the 1-Wire
         operations the platform but a good rule of thumb is 10 - 20ms
         per byte.

   WriteCOM
         Write a specified number of bytes to the serial COM port.

   FlushCOM 
         Allow any pending write operations to complete.  Clear any
         bytes read.

   BreakCOM
         Send a 'BREAK' on the serial COM port last at least 
         2 milliseconds.

   msDelay
         Delay at least the specified number of milliseconds.  This
         is used in the DS2480 detect sequence.

Optional API that may be needed for the platform or for a specific
application.

   OpenCOM
         Open the specified serial COM port for communication.  Most
         High-level OS's will need this.  If not needed then just
         return success.  Start the COM port out at 9600, N, 8, 1.

   CloseCOM
         Close the previously opened (OpenCOM) serial COM port. Most
         High-level OS's will need this.  

   SetCOMBaud
         Change the serial BAUD rate to the rate specified.  This need
         only be supported if Overdrive communication speeds are desired. 

   msGettick
         Return an increment millisecond counter.  This is used in several
         of the sample applications.