Index: twisted/internet/serialport.py
===================================================================
--- twisted/internet/serialport.py	(revision 29075)
+++ twisted/internet/serialport.py	(working copy)
@@ -4,6 +4,15 @@
 
 """
 Serial Port Protocol
+
+pySerial is required for all platforms: http://pyserial.sourceforge.net/
+
+Windows requires the use of a reactor that supports
+L{twisted.internet.interfaces.IReactorWin32Events}
+e.g. L{twisted.internet.win32eventreactor}
+
+pywin32 (previously win32all) is also required for Windows:
+http://sourceforge.net/projects/pywin32/
 """
 
 # http://twistedmatrix.com/trac/ticket/3725#comment:24
@@ -63,6 +72,56 @@
         self._serial.setRTS(on)
 
 class SerialPort(BaseSerialPort):
+    """
+     Initialize the SerialPort
+     Serial parameters are passed through to the underlying 
+     pyserial Serial constructor
+     
+     @param protocol: Protocol to use with the serial transport
+     @type protocol: type which implements L{IProtocol}
+     
+     @param deviceNameOrPortNumber: OS-specific device name or number. e.g.
+                                    device number, starting at zero
+                                    '/dev/ttyUSB0' on GNU/Linux
+                                    'COM3' on Windows
+     @type deviceNameOrPortNumber: C{str} or C{int}
+     
+     @param reactor: The reactor to use. On Windows, must implement 
+                    L{twisted.internet.interfaces.IReactorWin32Events}
+                    e.g. L{twisted.internet.win32eventreactor}
+     @type reactor: type which implements L{IReactor}.
+
+     @param baudrate: baudrate
+     @type baudrate: C{int}
+     
+     @param bytesize: number of databits
+     @type bytesize: C{int}
+     
+     @param parity: enable parity checking
+     @type parity: C{str}
+     
+     @param stopbits: number of stopbits
+     @type stopbits: C{int}
+     
+     @param timeout: set a read timeout value (not implemented on win32)
+     @type timeout: C{int} or C{float}
+     
+     @param xonxoff: enable software flow control (0/1)
+     @type xonxoff: C{int}
+     
+     @param rtscts: enable RTS/CTS flow control (0/1)
+     @type rtscts: C{int}
+     
+     @raise ValueError: On Windows, if the reactor does not support 
+                        L{twisted.internet.interfaces.IReactorWin32Events}
+                        e.g. L{twisted.internet.win32eventreactor}
+
+     @raise ValueError: Will be raised when serial parameters are out of range,
+                        e.g baudrate, bytesize, etc.
+
+     @raise SerialException: In case the device can not be found or 
+                             can not be configured
+     """
     pass
 
 # replace SerialPort with appropriate serial port