Add a mini example about using cu(1) to connect to a serial port.

Requested by:	   Soeren Straarup <xride@x12.dk>
Assisted by:	   Daniel Gerzo <danger@rulez.sk>

en_US.ISO8859-1/books/handbook/serialcomms/chapter.sgml

@@ -746,6 +746,42 @@ sio3: type 16550A</screen>
 	  spouse is busy working on your FreeBSD system's console, you can do
 	  some text-only work at the same time from a less powerful personal
 	  computer hooked up as a terminal to the FreeBSD system.</para>
+
+	<para>There are at least two utilities in the base-system of
+	  &os; that can be used to work through a serial connection:
+	  &man.cu.1; and &man.tip.1;.</para>
+
+	<para>To connect from a client system that runs &os; to the
+	  serial connection of another system, you can use:</para>
+
+	<screen>&prompt.root; <userinput>cu -l <replaceable>serial-port-device</replaceable></userinput></screen>
+
+	<para>Where <quote>serial-port-device</quote> is the name a
+	  special device file denoting a serial port of your system.
+	  These device files are called
+	  <devicename>/dev/cuaa<replaceable>N</replaceable></devicename>
+	  for &os; versions older than 6.0, and
+	  <devicename>/dev/cuad<replaceable>N</replaceable></devicename>
+	  for 6.0 and later versions.</para>
+
+	<para>The <quote>N</quote>-part of a device name is the serial
+	  port number.</para>
+
+	<note>
+	  <para>Note that device numbers in &os; start from zero and not
+	    one (like they do, for instance in DOS-derived systems).
+	    This means that what DOS-based systems
+	    call <quote>COM1</quote> is
+	    usually <filename>/dev/cuad0</filename> in &os;.</para>
+	</note>
+
+	<note>
+	  <para>Some people prefer to use other programs, available
+	    through the Ports Collection.  The Ports include quite a few
+	    utilities which can work in ways similar to &man.cu.1; and
+	    &man.tip.1;,
+	    i.e. <filename role="package">comms/minicom</filename>.</para>
+	</note>
       </sect3>
 
       <sect3 id="term-x">