svn commit: r41052 - head/en_US.ISO8859-1/books/handbook/serialcomms

Dru Lavigne dru at FreeBSD.org
Wed Feb 27 20:38:17 UTC 2013


Author: dru
Date: Wed Feb 27 20:38:17 2013
New Revision: 41052
URL: http://svnweb.freebsd.org/changeset/doc/41052

Log:
  First pass at this chapter. This patch addresses the following:
  
  - &os;, you, and please
  
  - fix xref, acronym, and directory tags (still needs ulink review)
  
  - removed redundant warning, leaving only first instance; this warning can be removed altogether once 7.x is EOL at end of month
  
  Approved by:  bcr (mentor)

Modified:
  head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml

Modified: head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml
==============================================================================
--- head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml	Tue Feb 26 16:52:43 2013	(r41051)
+++ head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml	Wed Feb 27 20:38:17 2013	(r41052)
@@ -13,31 +13,28 @@
 
     <indexterm><primary>serial communications</primary></indexterm>
 
-    <para>&unix; has always had support for serial communications.  In
-      fact, the very first &unix; machines relied on serial lines for
-      user input and output.  Things have changed a lot from the days
-      when the average <quote>terminal</quote> consisted of a
-      10-character-per-second serial printer and a keyboard.  This
-      chapter will cover some of the ways in which FreeBSD uses serial
-      communications.</para>
+    <para>&unix; has always had support for serial communications as
+      the very first &unix; machines relied on serial lines for user
+      input and output.  Things have changed a lot from the days
+      when the average terminal consisted of a 10-character-per-second
+      serial printer and a keyboard.  This chapter covers some of the
+      ways serial communications can be used on &os;.</para>
 
     <para>After reading this chapter, you will know:</para>
 
     <itemizedlist>
       <listitem>
-	<para>How to connect terminals to your FreeBSD
-	  system.</para>
+	<para>How to connect terminals to a &os; system.</para>
       </listitem>
       <listitem>
-	<para>How to use a modem to dial out to remote
-	  hosts.</para>
+	<para>How to use a modem to dial out to remote hosts.</para>
       </listitem>
       <listitem>
-	<para>How to allow remote users to login to your
-	  system with a modem.</para>
+	<para>How to allow remote users to login to a &os; system
+	  with a modem.</para>
       </listitem>
       <listitem>
-	<para>How to boot your system from a serial console.</para>
+	<para>How to boot a &os; system from a serial console.</para>
       </listitem>
     </itemizedlist>
 
@@ -45,17 +42,16 @@
 
     <itemizedlist>
       <listitem>
-	<para>Know how to configure and install a new kernel (<xref
-	    linkend="kernelconfig"/>).</para>
+	<para>Know how to <link linkend="kernelconfig"> configure and
+	    install a custom kernel</link>.</para>
       </listitem>
       <listitem>
-	<para>Understand &unix; permissions and processes (<xref
-	    linkend="basics"/>).</para>
+	<para>Understand <link linkend="basics"> &os; permissions
+	    and processes</link>.</para>
       </listitem>
       <listitem>
 	<para>Have access to the technical manual for the serial
-	  hardware (modem or multi-port card) that you would like to
-	  use with FreeBSD.</para>
+	  hardware to be used with &os;.</para>
       </listitem>
     </itemizedlist>
   </sect1>
@@ -82,30 +78,30 @@
       <variablelist>
 	<indexterm><primary>bits-per-second</primary></indexterm>
 	<varlistentry>
-	  <term>bps</term>
+	  <term><acronym>bps</acronym></term>
 	  <listitem>
-	    <para>Bits per Second — the rate at which data is
-	      transmitted</para>
+	    <para>Bits per Second (<acronym>bps</acronym>) is the rate
+	      at which data is transmitted.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
-	  <term>DTE</term>
+	  <term><acronym>DTE</acronym></term>
 	  <listitem>
 	    <indexterm><primary>DTE</primary></indexterm>
 
-	    <para>Data Terminal Equipment — for example, your
-	      computer</para>
+	    <para>An example of a Data Terminal Equipment
+	      (<acronym>DTE</acronym>) is a computer.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
-	  <term>DCE</term>
+	  <term><acronym>DCE</acronym></term>
 	  <listitem>
 	    <indexterm><primary>DCE</primary></indexterm>
 
-	    <para>Data Communications Equipment — your
-	      modem</para>
+	    <para>An example of a Data Communications Equipment
+	      (<acronym>DTE</acronym>) is a modem.</para>
 	  </listitem>
 	</varlistentry>
 
@@ -115,8 +111,9 @@
 	  <listitem>
 	    <indexterm><primary>RS-232C cables</primary></indexterm>
 
-	    <para>EIA standard for hardware serial
-	      communications</para>
+	    <para>The original standard for hardware serial
+	      communications.  It is now usually referred to as
+	      <acronym>TIA</acronym>-232</para>
 	  </listitem>
 	</varlistentry>
       </variablelist>
@@ -124,28 +121,26 @@
       <para>When talking about communications data rates, this section
 	does not use the term <quote>baud</quote>.  Baud refers to the
 	number of electrical state transitions that may be made in a
-	period of time, while <quote>bps</quote> (bits per second) is
-	the <emphasis>correct</emphasis> term to use (at least it does
-	not seem to bother the curmudgeons quite as much).</para>
+	period of time, while <acronym>bps</acronym> is the
+	<emphasis>correct</emphasis> term to use.</para>
     </sect2>
 
     <sect2 id="serial-cables-ports">
       <title>Cables and Ports</title>
 
-      <para>To connect a modem or terminal to your FreeBSD system, you
-	will need a serial port on your computer and the proper cable
-	to connect to your serial device.  If you are already familiar
-	with your hardware and the cable it requires, you can safely
-	skip this section.</para>
+      <para>To connect a modem or serial terminal to a &os; system, a
+	serial port on the computer and the proper cable to connect to
+	the serial device are needed.  Users who are already familiar
+	with serial hardware and cabling can safely skip this
+	section.</para>
 
       <sect3 id="term-cables">
 	<title>Cables</title>
 
 	<para>There are several different kinds of serial cables.  The
-	  two most common types for our purposes are null-modem cables
-	  and standard (<quote>straight</quote>) RS-232 cables.  The
-	  documentation for your hardware should describe the type of
-	  cable required.</para>
+	  two most common types are null-modem cables and standard
+	  RS-232 cables.  The documentation for the hardware should
+	  describe the type of cable required.</para>
 
 	<sect4 id="term-cables-null">
 	  <title>Null-modem Cables</title>
@@ -160,16 +155,15 @@
 	    <quote>Transmitted Data</quote> pin on one end goes to the
 	    <quote>Received Data</quote> pin on the other end.</para>
 
-	  <para>You can also construct your own null-modem cable for
-	    use with terminals (e.g., for quality purposes).  This
-	    table shows the RS-232C <link
-	      linkend="serialcomms-signal-names">signals</link>
-	    and the pin numbers on a DB-25 connector.  Note that the
-	    standard also calls for a straight-through pin 1 to pin 1
-	    <emphasis>Protective Ground</emphasis> line, but it is
-	    often omitted.  Some terminals work OK using only pins 2,
-	    3 and 7, while others require different configurations
-	    than the examples shown below.</para>
+	  <para>A null-modem cable can be constructed for use with
+	    terminals.  The following table shows the RS-232C <link
+	      linkend="serialcomms-signal-names">signal names</link>
+	    and the pin numbers on a DB-25 connector.  While the
+	    standard calls for a straight-through pin 1 to pin 1
+	    <emphasis>Protective Ground</emphasis> line, it is often
+	    omitted.  Some terminals work using only pins 2, 3, and
+	    7, while others require different configurations than
+	    the examples shown below.</para>
 
 	  <table frame="none" pgwide="1">
 	    <title>DB-25 to DB-25 Null-Modem Cable</title>
@@ -261,8 +255,8 @@
 	    </tgroup>
 	  </table>
 
-	  <para>Here are two other schemes more common
-	    nowadays.</para>
+	  <para>The next two tables show two other common
+	    schemes.</para>
 
 	  <table frame="none" pgwide="1">
 	    <title>DB-9 to DB-9 Null-Modem Cable</title>
@@ -451,10 +445,9 @@
 	      and a long wire to the other single pin.</para>
 	  </note>
 
-	  <para>The above designs seems to be the most popular.  In
-	    another variation (explained in the book <emphasis>RS-232
-	      Made Easy</emphasis>) SG connects to SG, TD connects to
-	    RD, RTS and CTS connect to DCD, DTR connects to DSR, and
+	  <para>The above designs seem to be the most popular.  In
+	    another variation, SG connects to SG, TD connects to RD,
+	    RTS and CTS connect to DCD, DTR connects to DSR, and
 	    vice-versa.</para>
 	</sect4>
 
@@ -464,11 +457,11 @@
 	  <indexterm><primary>RS-232C cables</primary></indexterm>
 
 	  <para>A standard serial cable passes all of the RS-232C
-	    signals straight through.  That is, the <quote>Transmitted
+	    signals straight through.  The <quote>Transmitted
 	      Data</quote> pin on one end of the cable goes to the
 	    <quote>Transmitted Data</quote> pin on the other end.
-	    This is the type of cable to use to connect a modem to
-	    your FreeBSD system, and is also appropriate for some
+	    This is the type of cable used to connect a modem to
+	    the &os; system, and is also appropriate for some
 	    terminals.</para>
 	</sect4>
       </sect3>
@@ -477,61 +470,61 @@
 	<title>Ports</title>
 
 	<para>Serial ports are the devices through which data is
-	  transferred between the FreeBSD host computer and the
+	  transferred between the &os; host computer and the
 	  terminal.  This section describes the kinds of ports that
-	  exist and how they are addressed in FreeBSD.</para>
+	  exist and how they are addressed in &os;.</para>
 
 	<sect4 id="term-portkinds">
 	  <title>Kinds of Ports</title>
 
-	  <para>Several kinds of serial ports exist.  Before you
-	    purchase or construct a cable, you need to make sure it
-	    will fit the ports on your terminal and on the FreeBSD
+	  <para>Several kinds of serial ports exist.  Before
+	    purchasing or constructing a cable, make sure it will
+	    fit the ports on the terminal and on the &os;
 	    system.</para>
 
-	  <para>Most terminals will have DB-25 ports.  Personal
-	    computers, including PCs running FreeBSD, will have DB-25
-	    or DB-9 ports.  If you have a multiport serial card for
-	    your PC, you may have RJ-12 or RJ-45 ports.</para>
+	  <para>Most terminals have DB-25 ports.  Personal computers
+	    may have DB-25 or DB-9 ports.  A multiport serial card may
+	    have RJ-12 or RJ-45 ports.</para>
 
 	  <para>See the documentation that accompanied the hardware
-	    for specifications on the kind of port in use.  A visual
-	    inspection of the port often works too.</para>
+	    for specifications on the kind of port or visually verify
+	    the type of port.</para>
 	</sect4>
 
 	<sect4 id="term-portnames">
 	  <title>Port Names</title>
 
-	  <para>In FreeBSD, you access each serial port through an
-	    entry in the <filename>/dev</filename> directory.  There
-	    are two different kinds of entries:</para>
+	  <para>In &os;, each serial port is accessed through an
+	    entry in <filename class="directory">/dev</filename>.
+	    There are two different kinds of entries:</para>
 
 	  <itemizedlist>
 	    <listitem>
 	      <para>Call-in ports are named
 		<filename>/dev/ttyu<replaceable>N</replaceable></filename>
 		where <replaceable>N</replaceable> is the port number,
-		starting from zero.  Generally, you use the call-in
-		port for terminals.  Call-in ports require that the
-		serial line assert the data carrier detect (DCD)
-		signal to work correctly.</para>
+		starting from zero.  Generally, the call-in port is
+		used for terminals.  Call-in ports require that the
+		serial line assert the Data Carrier Detect
+		(<acronym>DCD</acronym>) signal to work
+		correctly.</para>
 	    </listitem>
 
 	    <listitem>
 	      <para>Call-out ports are named
 		<filename>/dev/cuau<replaceable>N</replaceable></filename>.
-		You usually do not use the call-out port for
-		terminals, just for modems.  You may use the call-out
-		port if the serial cable or the terminal does not
-		support the carrier detect signal.</para>
+		Call-out ports are usually not used for terminals, but
+		are used for modems.  The call-out port can be used if
+		the serial cable or the terminal does not support the
+		carrier detect signal.</para>
 	    </listitem>
 	  </itemizedlist>
 
-	  <para>If you have connected a terminal to the first serial
-	    port(<devicename>COM1</devicename> in &ms-dos;), then you
-	    will use <filename>/dev/ttyu0</filename> to refer to the
+	  <para>If a terminal is connected to the first serial
+	    port(<devicename>COM1</devicename>), use
+	    <filename>/dev/ttyu0</filename> to refer to the
 	    terminal.  If the terminal is on the second serial port
-	    (also known as <devicename>COM2</devicename>), use
+	    (<devicename>COM2</devicename>), use
 	    <filename>/dev/ttyu1</filename>, and so forth.</para>
 
 	</sect4>
@@ -541,25 +534,25 @@
     <sect2>
       <title>Kernel Configuration</title>
 
-      <para>FreeBSD supports four serial ports by default.  In the
+      <para>&os; supports four serial ports by default.  In the
 	&ms-dos; world, these are known as
 	<devicename>COM1</devicename>,
 	<devicename>COM2</devicename>,
 	<devicename>COM3</devicename>, and
-	<devicename>COM4</devicename>.  FreeBSD currently supports
+	<devicename>COM4</devicename>.  &os; currently supports
 	<quote>dumb</quote> multiport serial interface cards, such as
-	the BocaBoard 1008 and 2016, as well as more
-	intelligent multi-port cards such as those made by Digiboard
-	and Stallion Technologies.  However, the default kernel only
-	looks for the standard COM ports.</para>
-
-      <para>To see if your kernel recognizes any of your serial ports,
-	watch for messages while the kernel is booting, or use the
-	<command>/sbin/dmesg</command> command to replay the kernel's
-	boot messages.  In particular, look for messages that start
-	with the characters <literal>uart</literal> if you use
-	&os; 8.0 or higher, or <literal>sio</literal> for
-	&os; 7.4 or older.</para>
+	the BocaBoard 1008 and 2016, as well as more intelligent
+	multi-port cards such as those made by Digiboard and Stallion
+	Technologies.  However, the default kernel only looks for the
+	standard COM ports.</para>
+
+      <para>To see if the kernel recognizes the serial ports,
+	watch for messages while the kernel is booting, or use
+	<command>/sbin/dmesg</command> to replay the kernel's
+	boot messages.  Look for messages that start with the
+	characters <literal>uart</literal> for &os; 8.0 or
+	higher, or <literal>sio</literal> for &os; 7.4 or
+	older.</para>
 
       <tip><para>To view just the messages that have the word
 	<literal>uart</literal> or <literal>sio</literal> depending
@@ -570,7 +563,7 @@
       </tip>
 
       <para>For example, on a &os; 7.<replaceable>X</replaceable>
-	system with four serial ports, these are the serial-port
+	system with four serial ports, these are the serial port
 	specific kernel boot messages:</para>
 
       <screen>sio0 at 0x3f8-0x3ff irq 4 on isa
@@ -582,31 +575,30 @@ sio2: type 16550A
 sio3 at 0x2e8-0x2ef irq 9 on isa
 sio3: type 16550A</screen>
 
-      <para>If your kernel does not recognize all of your serial
-	ports, you will probably need to configure your kernel
-	in the <filename>/boot/device.hints</filename> file.  You can
-	also comment-out or completely remove lines for devices you
-	do not have.</para>
-
-      <para>Please refer to the &man.sio.4; manual page for
-	more information on serial ports and multiport boards
-	configuration.  Be careful if you are using a configuration
-	file that was previously used for a different version of
-	FreeBSD because the device flags and the syntax have changed
-	between versions.</para>
+      <para>If the kernel does not recognize all of the serial
+	ports, configure <filename>/boot/device.hints</filename>.
+	When editing this file, one can comment out or completely
+	remove lines for devices that do not exist on the
+	system.</para>
+
+      <para>Refer to &man.sio.4; for more information on
+	configuring serial ports and multiport boards.  When using a
+	configuration file that was previously used for a different
+	version of &os; be aware that the device flags and the syntax
+	may have changed between versions.</para>
 
       <note>
 	<para><literal>port IO_COM1</literal> is a substitution for
 	  <literal>port 0x3f8</literal>, <literal>IO_COM2</literal> is
 	  <literal>0x2f8</literal>, <literal>IO_COM3</literal> is
 	  <literal>0x3e8</literal>, and <literal>IO_COM4</literal> is
-	  <literal>0x2e8</literal>, which are fairly common port
-	  addresses for their respective serial ports; interrupts 4,
-	  3, 5, and 9 are fairly common interrupt request lines.  Also
-	  note that regular serial ports <emphasis>cannot</emphasis>
-	  share interrupts on ISA-bus PCs (multiport boards have
+	  <literal>0x2e8</literal>.  These are fairly common port
+	  addresses for their respective serial ports and interrupts
+	  4, 3, 5, and 9 are fairly common interrupt request lines.
+	  Regular serial ports <emphasis>cannot</emphasis> share
+	  interrupts on ISA-bus PCs.  Multiport boards have
 	  on-board electronics that allow all the 16550A's on the
-	  board to share one or two interrupt request lines).</para>
+	  board to share one or two interrupt request lines.</para>
       </note>
 
     </sect2>
@@ -615,13 +607,13 @@ sio3: type 16550A</screen>
       <title>Device Special Files</title>
 
       <para>Most devices in the kernel are accessed through
-	<quote>device special files</quote>, which are located in the
-	<filename>/dev</filename> directory.  The
+	<quote>device special files</quote> which are located in
+	<filename>/dev class="directory"</filename>.  The
 	<devicename>sio</devicename> devices are accessed through the
 	<filename>/dev/ttyu<replaceable>N</replaceable></filename>
 	(dial-in) and
 	<filename>/dev/cuau<replaceable>N</replaceable></filename>
-	(call-out) devices.  FreeBSD also provides initialization
+	(call-out) devices.  &os; also provides initialization
 	devices
 	(<filename>/dev/ttyu<replaceable>N</replaceable>.init</filename>
 	and
@@ -635,9 +627,9 @@ sio3: type 16550A</screen>
 	such as <literal>crtscts</literal> for modems which use
 	<literal>RTS/CTS</literal> signaling for flow control.  The
 	locking devices are used to lock flags on ports to prevent
-	users or programs changing certain parameters; see the manual
-	pages &man.termios.4;, &man.sio.4;, and &man.stty.1; for
-	information on the terminal settings, locking and initializing
+	users or programs changing certain parameters.  Refer to
+	&man.termios.4;, &man.sio.4;, and &man.stty.1; for
+	information on terminal settings, locking and initializing
 	devices, and setting terminal options, respectively.</para>
     </sect2>
 
@@ -651,20 +643,20 @@ sio3: type 16550A</screen>
       <para>The
 	<devicename>ttyu<replaceable>N</replaceable></devicename> (or
 	<devicename>cuau<replaceable>N</replaceable></devicename>)
-	device is the regular device you will want to open for your
-	applications.  When a process opens the device, it will have a
-	default set of terminal I/O settings.  You can see these
-	settings with the command</para>
+	is the regular device to open for applications.  When a
+	process opens the device, it will have a default set of
+	terminal I/O settings.  These settings can be viewed with the
+	command:</para>
 
       <screen>&prompt.root; <userinput>stty -a -f /dev/ttyu1</userinput></screen>
 
-      <para>When you change the settings to this device, the settings
-	are in effect until the device is closed.  When it is
-	reopened, it goes back to the default set.  To make changes to
-	the default set, you can open and adjust the settings of the
+      <para>When the settings are changed for a device, the settings
+	are in effect until the device is closed.  When the device is
+	reopened, it goes back to the default set.  To permanently
+	change the default set, open and adjust the settings of the
 	<quote>initial state</quote> device.  For example, to turn on
 	<option>CLOCAL</option> mode, 8 bit communication, and
-	<option>XON/XOFF</option> flow control by default for
+	<option>XON/XOFF</option> flow control for
 	<devicename>ttyu5</devicename>, type:</para>
 
     <screen>&prompt.root; <userinput>stty -f /dev/ttyu5.init clocal cs8 ixon ixoff</userinput></screen>
@@ -674,8 +666,8 @@ sio3: type 16550A</screen>
 	<secondary><filename>rc.serial</filename></secondary>
       </indexterm>
 
-      <para>System-wide initialization of the serial devices is
-	controlled in <filename>/etc/rc.d/serial</filename>.  This
+      <para>System-wide initialization of serial devices is
+	controlled by <filename>/etc/rc.d/serial</filename>.  This
 	file affects the default settings of serial devices.</para>
 
       <para>To prevent certain settings from being changed by an
@@ -689,9 +681,8 @@ sio3: type 16550A</screen>
 	<devicename>ttyu5</devicename> and tries to change the speed
 	of the port will be stuck with 57600 bps.</para>
 
-      <para>Naturally, you should make the initial state and lock
-	state devices writable only by the <username>root</username>
-	account.</para>
+      <para>The initial state and lock state devices should only be
+	writable by <username>root</username>.</para>
     </sect2>
   </sect1>
 
@@ -708,120 +699,85 @@ sio3: type 16550A</screen>
     </sect1info>
     <title>Terminals</title>
 
-    <warning>
-      <para>As of &os; 8.0, device nodes for serial ports have been
-	renamed from
-	<filename>/dev/cuad<replaceable>N</replaceable></filename> to
-	<filename>/dev/cuau<replaceable>N</replaceable></filename> and
-	from
-	<filename>/dev/ttyd<replaceable>N</replaceable></filename> to
-	<filename>/dev/ttyu<replaceable>N</replaceable></filename>.
-	&os; 7.X users will have to adapt the following
-	documentation according to these changes.</para>
-    </warning>
-
     <indexterm><primary>terminals</primary></indexterm>
 
     <para>Terminals provide a convenient and low-cost way to access
-      your FreeBSD system when you are not at the computer's console
-      or on a connected network.  This section describes how to use
-      terminals with FreeBSD.</para>
+      a &os; system when not at the computer's console or on a
+      connected network.  This section describes how to use terminals
+      with &os;.</para>
 
     <sect2 id="term-uses">
       <title>Uses and Types of Terminals</title>
 
       <para>The original &unix; systems did not have consoles.
-	Instead, people logged in and ran programs through terminals
-	that were connected to the computer's serial ports.  It is
-	quite similar to using a modem and terminal software to dial
-	into a remote system to do text-only work.</para>
-
-      <para>Today's PCs have consoles capable of high quality
-	graphics, but the ability to establish a login session on a
-	serial port still exists in nearly every &unix; style
-	operating system today; FreeBSD is no exception.  By using a
-	terminal attached to an unused serial port, you can log in and
-	run any text program that you would normally run on the
-	console or in an <command>xterm</command> window in the X
-	Window System.</para>
-
-      <para>For the business user, you can attach many terminals to a
-	FreeBSD system and place them on your employees' desktops.
-	For a home user, a spare computer such as an older IBM PC or a
-	&macintosh; can be a terminal wired into a more powerful
-	computer running FreeBSD. You can turn what might otherwise be
-	a single-user computer into a powerful multiple user
-	system.</para>
-
-      <para>For FreeBSD, there are three kinds of terminals:</para>
+	Instead, users logged in and ran programs through terminals
+	that were connected to the computer's serial ports.</para>
 
-      <itemizedlist>
-	<listitem>
-	  <para><link linkend="term-dumb">Dumb terminals</link></para>
-	</listitem>
-
-	<listitem>
-	  <para><link linkend="term-pcs">PCs acting as
-	      terminals</link></para>
-	</listitem>
-
-	<listitem>
-	  <para><link linkend="term-x">X terminals</link></para>
-	</listitem>
-      </itemizedlist>
-
-      <para>The remaining subsections describe each kind.</para>
+      <para>The ability to establish a login session on a serial port
+	still exists in nearly every &unix;-like operating system
+	today, including &os;.  By using a terminal attached to an
+	unused serial port, a user can log in and run any text program
+	that can normally be run on the console or in an
+	<command>xterm</command> window.</para>
+
+      <para>Many terminals can be attached to a &os; system.  An older
+	spare computer can be used as a terminal wired into a more
+	powerful computer running &os;.  This can turn what might
+	otherwise be a single-user computer into a powerful multiple
+	user system.</para>
+
+      <para>This section describes three kinds of terminals supported
+	by &os;: dumb terminals, computers acting as terminals, and X
+	terminals.</para>
 
       <sect3 id="term-dumb">
 	<title>Dumb Terminals</title>
 
-	<para>Dumb terminals are specialized pieces of hardware that
-	  let you connect to computers over serial lines.  They are
-	  called <quote>dumb</quote> because they have only enough
-	  computational power to display, send, and receive text.  You
-	  cannot run any programs on them.  It is the computer to
-	  which you connect them that has all the power to run text
+	<para>Dumb terminals are specialized hardware that connect to
+	  computers over serial lines.  They are called
+	  <quote>dumb</quote> because they have only enough
+	  computational power to display, send, and receive text.  No
+	  programs can be run on these devices.  Dumb terminals
+	  connect to a computer that has all the power to run text
 	  editors, compilers, email, games, and so forth.</para>
 
 	<para>There are hundreds of kinds of dumb terminals made by
-	  many manufacturers, including Digital Equipment
-	  Corporation's VT-100 and Wyse's WY-75.  Just about any kind
-	  will work with FreeBSD. Some high-end terminals can even
-	  display graphics, but only certain software packages can
-	  take advantage of these advanced features.</para>
+	  many manufacturers, and just about any kind will work with
+	  &os;.  Some high-end terminals can even display graphics,
+	  but only certain software packages can take advantage of
+	  these advanced features.</para>
 
 	<para>Dumb terminals are popular in work environments where
-	  workers do not need access to graphical applications such as
-	  those provided by the X Window System.</para>
+	  workers do not need access to graphical applications.</para>
       </sect3>
 
       <sect3 id="term-pcs">
-	<title>PCs Acting as Terminals</title>
+	<title>Computers Acting as Terminals</title>
 
 	<para>If a <link linkend="term-dumb">dumb terminal</link> has
-	  just enough ability to display, send, and receive text, then
-	  certainly any spare personal computer can be a dumb
-	  terminal.  All you need is the proper cable and some
-	  <emphasis>terminal emulation</emphasis> software to run on
-	  the computer.</para>
-
-	<para>Such a configuration is popular in homes.  For example,
-	  if your 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>
+	  just enough ability to display, send, and receive text,
+	  any spare computer can be a dumb terminal.  All that is
+	  needed is the proper cable and some <emphasis>terminal
+	    emulation</emphasis> software to run on the
+	  computer.</para>
+
+	<para>This configuration can be useful.  For example, if one
+	  user is busy working at the &os; system's console, another
+	  user can do some text-only work at the same time from a
+	  less powerful personal computer hooked up as a terminal to
+	  the &os; 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>
+	  serial connection of another system, 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 of a
-	  special device file denoting a serial port of your system.
+	  special device file denoting a serial port on the system.
 	  These device files are called
 	  <devicename>/dev/cuau<replaceable>N</replaceable></devicename>.</para>
 
@@ -830,17 +786,13 @@ sio3: type 16550A</screen>
 
 	<note>
 	  <para>Note that device numbers in &os; start from zero and
-	    not one (like they do, for instance in &ms-dos;-derived
-	    systems).  This means that what &ms-dos;-based systems
-	    call <devicename>COM1</devicename> is usually
+	    not one.  This means that <devicename>COM1</devicename> is
 	    <filename>/dev/cuau0</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
+	  <para>Some people prefer to use other programs available
+	    through the Ports Collection, such as <filename
 	      role="package">comms/minicom</filename>.</para>
 	</note>
       </sect3>
@@ -854,48 +806,44 @@ sio3: type 16550A</screen>
 	  being relegated to text-only applications, they can display
 	  any X application.</para>
 
-	<para>We introduce X terminals just for the sake of
-	  completeness.  However, this chapter does
-	  <emphasis>not</emphasis> cover setup, configuration, or use
-	  of X terminals.</para>
+	<para>This chapter does <emphasis>not</emphasis> cover the
+	  setup, configuration, or use of X terminals.</para>
       </sect3>
     </sect2>
 
     <sect2 id="term-config">
       <title>Configuration</title>
 
-      <para>This section describes what you need to configure on your
-	FreeBSD system to enable a login session on a terminal.  It
-	assumes you have already configured your kernel to support the
-	serial port to which the terminal is connected—and that
-	you have connected it.</para>
-
-      <para>Recall from <xref linkend="boot"/> that the
-	<command>init</command> process is responsible for all process
-	control and initialization at system startup.  One of the
-	tasks performed by <command>init</command> is to read the
-	<filename>/etc/ttys</filename> file and start a
+      <para>This section describes how to configure a &os; system to
+	enable a login session on a terminal.  It assumes that the
+	kernel is configured to support the serial port to which the
+	terminal is connected and that the terminal is
+	connected.</para>
+
+      <para>The <command>init</command> process is responsible for all
+	process control and initialization at system startup.  One of
+	the tasks performed by <command>init</command> is to read
+	<filename>/etc/ttys</filename> and start a
 	<command>getty</command> process on the available terminals.
 	The <command>getty</command> process is responsible for
 	reading a login name and starting the <command>login</command>
 	program.</para>
 
-      <para>Thus, to configure terminals for your FreeBSD system the
-	following steps should be taken as
-	<username>root</username>:</para>
+      <para>To configure terminals for a &os; system, the following
+	steps should be taken as <username>root</username>:</para>
 
       <procedure>
 	<step>
 	  <para>Add a line to <filename>/etc/ttys</filename> for the
-	    entry in the <filename>/dev</filename> directory for the
-	    serial port if it is not already there.</para>
+	    entry in <filename class="directory">/dev</filename> for
+	    the serial port if it is not already there.</para>
 	</step>
 
 	<step>
 	  <para>Specify that <command>/usr/libexec/getty</command>
 	    be run on the port, and specify the appropriate
-	    <replaceable>getty</replaceable> type from the
-	    <filename>/etc/gettytab</filename> file.</para>
+	    <replaceable>getty</replaceable> type from
+	    <filename>/etc/gettytab</filename>.</para>
 	</step>
 
 	<step>
@@ -912,53 +860,53 @@ sio3: type 16550A</screen>
 	</step>
 
 	<step>
-	  <para>Force <command>init</command> to reread the
-	    <filename>/etc/ttys</filename> file.</para>
+	  <para>Force <command>init</command> to reread
+	    <filename>/etc/ttys</filename>.</para>
 	</step>
       </procedure>
 
-      <para>As an optional step, you may wish to create a custom
+      <para>As an optional step, create a custom
 	<replaceable>getty</replaceable> type for use in step 2 by
-	making an entry in <filename>/etc/gettytab</filename>.  This
-	chapter does not explain how to do so; you are encouraged to
-	see the &man.gettytab.5; and the &man.getty.8; manual pages
-	for more information.</para>
+	making an entry in <filename>/etc/gettytab</filename>.  For
+	more information, refer to &man.gettytab.5; and
+	&man.getty.8;.</para>
 
       <sect3 id="term-etcttys">
 	<title>Adding an Entry to
 	  <filename>/etc/ttys</filename></title>
 
-	<para>The <filename>/etc/ttys</filename> file lists all of the
-	  ports on your FreeBSD system where you want to allow logins.
-	  For example, the first virtual console
-	  <devicename>ttyv0</devicename> has an entry in this file.
-	  You can log in on the console using this entry.  This
-	  file also contains entries for the other virtual consoles,
-	  serial ports, and pseudo-ttys.  For a hardwired terminal,
-	  just list the serial port's <filename>/dev</filename> entry
-	  without the <filename>/dev</filename> part (for example,
+	<para><filename>/etc/ttys</filename> lists all of the ports
+	  on the &os; system which allow logins.  For example, the
+	  first virtual console,
+	  <devicename>ttyv0</devicename>, has an entry in this file,
+	  allowing logins on the console.  This file also contains
+	  entries for the other virtual consoles, serial ports, and
+	  pseudo-ttys.  For a hardwired terminal,
+	  list the serial port's <filename
+	    class="directory">/dev</filename> entry without the
+	  <literal>/dev</literal> part.  For example,
 	  <filename>/dev/ttyv0</filename> would be listed as
-	  <devicename>ttyv0</devicename>).</para>
+	  <literal>ttyv0</literal>.</para>
 
-	<para>A default FreeBSD install includes an
-	  <filename>/etc/ttys</filename> file with support for the
+	<para>A default &os; install includes an
+	  <filename>/etc/ttys</filename> with support for the
 	  first four serial ports: <devicename>ttyu0</devicename>
-	  through <devicename>ttyu3</devicename>.  If you are
-	  attaching a terminal to one of those ports, you do not need
-	  to add another entry.</para>
+	  through <devicename>ttyu3</devicename>.  When
+	  attaching a terminal to one of those ports, this file does
+	  not need to be edited.</para>
 
 	<example id="ex-etc-ttys">
 	  <title>Adding Terminal Entries to
 	    <filename>/etc/ttys</filename></title>
 
-	  <para>Suppose we would like to connect two terminals to the
-	    system: a Wyse-50 and an old 286 IBM PC running
+	  <para>This example configures two terminals: a Wyse-50 and
+	    an old 286 IBM PC running
 	    <application>Procomm</application> terminal software
-	    emulating a VT-100 terminal.  We connect the Wyse to the
-	    second serial port and the 286 to the sixth serial port (a
-	    port on a multiport serial card).  The corresponding
-	    entries in the <filename>/etc/ttys</filename> file would
-	    look like this:</para>
+	    emulating a VT-100 terminal.  The Wyse is connected to the
+	    second serial port and the 286 to the sixth serial port on
+	    a multiport serial card.  The corresponding entries in
+	    <filename>/etc/ttys</filename> would look like
+	    this:</para>
 
 	  <programlisting>ttyu1<co
 	      id="co-ttys-line1col1"/>  "/usr/libexec/getty std.38400"<co
@@ -972,57 +920,56 @@ ttyu5   "/usr/libexec/getty std.19200"  
 	    <callout arearefs="co-ttys-line1col1">
 	      <para>The first field normally specifies the name of
 		the terminal special file as it is found in
-		<filename>/dev</filename>.</para>
+		<filename class="directory">/dev</filename>.</para>
 	    </callout>
 
 	    <callout arearefs="co-ttys-line1col2">
 	      <para>The second field is the command to execute for
 		this line, which is usually &man.getty.8;.
 		<command>getty</command> initializes and opens the
-		line, sets the speed, prompts for a user name and then
-		executes the &man.login.1; program.</para>
+		line, sets the speed, prompts for a user name, and
+		then executes &man.login.1;.</para>
 
 	      <para>The <command>getty</command> program accepts one
 		(optional) parameter on its command line, the
 		<replaceable>getty</replaceable> type.  A
 		<replaceable>getty</replaceable> type configures
-		characteristics on the terminal line, like bps rate
-		and parity.  The <command>getty</command> program
-		reads these characteristics from the file
-		<filename>/etc/gettytab</filename>.</para>
-
-	      <para>The file <filename>/etc/gettytab</filename>
-		contains lots of entries for terminal lines both old
-		and new.  In almost all cases, the entries that start
-		with the text <literal>std</literal> will work for
-		hardwired terminals.  These entries ignore parity.
-		There is a <literal>std</literal> entry for each bps
-		rate from 110 to 115200.  Of course, you can add your
-		own entries to this file.  The &man.gettytab.5; manual
-		page provides more information.</para>
+		characteristics on the terminal line, like
+		<acronym>bps</acronym> rate and parity.
+		<command>getty</command> reads these characteristics
+		from <filename>/etc/gettytab</filename>.</para>
+
+	      <para><filename>/etc/gettytab</filename> contains many
+		entries for terminal lines, both old and new.  In
+		almost all cases, the entries that start with the
+		text <literal>std</literal> will work for hardwired
+		terminals as these entries ignore parity.  There is
+		a <literal>std</literal> entry for each
+		<acronym>bps</acronym> rate from 110 to 115200.
+		&man.gettytab.5; provides more information.</para>
 
 	      <para>When setting the <replaceable>getty</replaceable>
-		type in the <filename>/etc/ttys</filename> file, make
-		sure that the communications settings on the terminal
+		type in <filename>/etc/ttys</filename>, make sure
+		that the communications settings on the terminal
 		match.</para>
 
-	      <para>For our example, the Wyse-50 uses no parity and
+	      <para>For this example, the Wyse-50 uses no parity and
 		connects at 38400 bps.  The 286 PC uses no
 		parity and connects at 19200 bps.</para>
 	    </callout>
 
 	    <callout arearefs="co-ttys-line1col3">
 	      <para>The third field is the type of terminal usually
-		connected to that tty line.  For dial-up ports,
+		connected to that terminal line.  For dial-up ports,
 		<literal>unknown</literal> or
-		<literal>dialup</literal> is typically used in this
-		field since users may dial up with practically any
-		type of terminal or software.  For hardwired
-		terminals, the terminal type does not change, so you
-		can put a real terminal type from the &man.termcap.5;
-		database file in this field.</para>
+		<literal>dialup</literal> is typically used since
+		users may dial up with practically any type of
+		terminal or software.  Since the terminal type does
+		not change for hardwired terminals, a real terminal
+		type from &man.termcap.5; can be used in this
+		field.</para>
 
-	      <para>For our example, the Wyse-50 uses the real
+	      <para>For this example, the Wyse-50 uses the real
 		terminal type while the 286 PC running
 		<application>Procomm</application> will be set to
 		emulate at VT-100. </para>
@@ -1030,30 +977,31 @@ ttyu5   "/usr/libexec/getty std.19200"  
 
 	    <callout arearefs="co-ttys-line1col4">
 	      <para>The fourth field specifies if the port should be
-		enabled.  Putting <literal>on</literal> here will have
-		the <command>init</command> process start the program
-		in the second field, <command>getty</command>.  If you
-		put <literal>off</literal> in this field, there will
-		be no <command>getty</command>, and hence no logins on
-		the port.</para>
+		enabled.  If set to <literal>on</literal>, the
+		<command>init</command> process will start the program
+		in the second field, <command>getty</command>.  If
+		this field is set to <literal>off</literal>, there
+		will be no <command>getty</command>, and hence no
+		logins on the port.</para>
 	    </callout>
 
 	    <callout arearefs="co-ttys-line1col5">
 	      <para>The final field is used to specify whether the
-		port is secure.  Marking a port as secure means that
-		you trust it enough to allow the
-		<username>root</username> account (or any account with
-		a user ID of 0) to login from that port.  Insecure
-		ports do not allow <username>root</username> logins.
-		On an insecure port, users must login from
-		unprivileged accounts and then use &man.su.1; or a
-		similar mechanism to gain superuser privileges.</para>
-
-	      <para>It is highly recommended that you use
-		<quote>insecure</quote>
-		even for terminals that are behind locked doors.  It
-		is quite easy to login and use <command>su</command>
-		if you need superuser privileges.</para>
+		port is secure.  Marking a port as
+		<literal>secure</literal> means that it is trusted
+		enough to allow <username>root</username>, or any
+		account with a <acronym>UID</acronym> of 0, to login
+		from that port.  Insecure ports do not allow
+		<username>root</username> logins.  On an insecure
+		port, users must login from unprivileged accounts and
+		then use &man.su.1; or a similar mechanism to gain
+		superuser privileges.</para>
+
+	      <para>It is highly recommended to use
+		<literal>insecure</literal>, even for terminals that
+		are behind locked doors.  It is quite easy to login
+		and use <command>su</command> when superuser
+		privileges are needed.</para>
 	    </callout>
 	  </calloutlist>
 	</example>
@@ -1063,34 +1011,34 @@ ttyu5   "/usr/libexec/getty std.19200"  
 	<title>Force <command>init</command> to Reread
 	  <filename>/etc/ttys</filename></title>
 
-	<para>After making the necessary changes to the
-	  <filename>/etc/ttys</filename> file you should send a SIGHUP
+	<para>After making any changes to
+	  <filename>/etc/ttys</filename>, send a SIGHUP
 	  (hangup) signal to the <command>init</command> process to
-	  force it to re-read its configuration file.  For
-	  example:</para>
+	  force it to re-read its configuration file:</para>
 
 	<screen>&prompt.root; <userinput>kill -HUP 1</userinput></screen>
 
 	<note>
 	  <para><command>init</command> is always the first process
-	    run on a system, therefore it will always have PID
-	    1.</para>
+	    run on a system, therefore it will always have a process
+	    ID of 1.</para>
 	</note>
 
 	<para>If everything is set up correctly, all cables are in
 	  place, and the terminals are powered up, then a
 	  <command>getty</command> process should be running on each
-	  terminal and you should see login prompts on your terminals
-	  at this point.</para>
+	  terminal and login prompts should be available on each
+	  terminal.</para>
       </sect3>

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