updated

LDP/howto/linuxdoc/Text-Terminal-HOWTO.sgml

@@ -1,11 +1,14 @@
 <!doctype linuxdoc system>
 <article>
-<title> Text-Terminal-HOWTO </title>
+<title> Text-Terminal-HOWTO
 <author> David S. Lawyer <url url="mailto:dave@lafn.org">  
 
-<date> v1.15, October 2000 
+<date> v1.16, October 2000 
 <!--
 Change log:
+v1.16 October 2000 Thin clients+; NC Howtos; Correction of bad typo
+"text terminals are fully obsolete".  Meant to say "not fully
+obsolete".  typo Unbounded => Boundless "' )
 v1.15 October 2000 Thin Clients; some broken url's changed or deleted
 v1.14 October 2000 Suse distribution uses /etc/securetty (didn't
 formerly), url of terminfo source, Serial Terminal Linux, pseudo
@@ -144,9 +147,10 @@ sites see: <url url="http://linuxdoc.org/mirrors.html">.
 Various formats are available.  If you only want to quickly check the
 date of the latest version look at <url
 url="http://linuxdoc.org/HOWTO/Text-Terminal-HOWTO.html">.  The
-version your are currently reading is: v1.15, October 2000 .  New in this version
+version your are currently reading is: v1.16, October 2000 .  New in this version
-is: Thin Clients; some broken url's changed or
+is: Thin-clients+; NC Howtos; Correction of bad typo "text
-deleted. 
+terminals are fully obsolete".  Meant to say "not fully obsolete".
+typo Unbounded => Boundless;  
 
 <sect1> Related HOWTO's <label id="related_howtos">
 <p> Go to the websites shown above to get these.
@@ -154,9 +158,13 @@ deleted.
 <item> Serial-HOWTO has info on Multiport Serial Cards used for both
 terminals and banks of modems.  It has general technical info on the
 serial port including troubleshooting it.
+<item> MacTerminal mini-HOWTO
 <item> Modem-HOWTO 
 <item> Serial-Programming-HOWTO
+<item> NC mini-HOWTO
 <item> NCD-X-Terminal mini-HOWTO
+<item> NCD-HOWTO
+<item> Thinclient-HOWTO
 <item> Xterminal-HOWTO (unmaintained).  It's at <url url=
 "http://sunsite.unc.edu/pub/Linux/docs/HOWTO/unmaintained/mini/Xterminal">
 </itemize>
@@ -257,9 +265,10 @@ server, etc.
 
 Other names for text terminals are "serial terminal", "character-cell
 terminal", "ASCII/ANSI terminal", "asynchronous terminal", "data
-terminal", "video terminal" and "video display terminal" (VDT).  In
+terminal", "video terminal" and "video display terminal" (VDT) and
-olden days "video display unit" (VDU) was used for terminals but
+"green terminal" (since many used green displays).  In olden days
-strictly speaking, it excludes the keyboard.
+"video display unit" (VDU) was used for terminals but strictly
+speaking, it excludes the keyboard.
 
 "Block mode" was used exclusively by old IBM mainframe terminals but
 many modern terminals also have this capability (which is not used
@@ -283,22 +292,10 @@ display images.  One may form  arrows <--- and draw boxes with _ and
 |.  With special graphic character sets, even more is possible.  By
 using all the letters, one may produce "ascii graphics" art.  The term
 "graphics terminal" usually means a terminal that can display bit
-mapped images.  However, this term is sometimes applied to all
+mapped images.  However, this term is sometimes applied also to
 text-only terminals since text is a limited form of graphics.  <label
 id="vector_graphics">
 
-<sect1>  Thin Clients (Terminals ?)
-
-<p> These are either terminals or thin (minimal) computers.  In
-contrast to text-terminals, they all display a high-speed GUI.  They
-are dependent on higher power computers (servers) for their operation.
-For a true terminal, the computing work and disk storage will all be
-done on the server.  At the other extreme, most of this work and
-storage is done at the client but some things such as administration,
-still depend on the server.  Since the client here is not "thin" it's
-not clear that this is really a thin client.  Some claim that
-text-terminals are also thin clients.
-
 <sect2> Graphics Displays
 <p> There are two basic types of graphics displays: raster and vector
 (rarely used).  Raster graphics (bit-mapped) puts dots on the screen
@@ -308,74 +305,136 @@ intended to be used for monochrome screens that don't have any dots.
 They use smart electronics to draw lines and curves with an electron
 beam that can move in any direction (at any angle and location).  True
 vector graphics draws high quality lines without zig-zags but is both
-rare and expensive.  Raster graphics is almost universally used today.
+rare and expensive.  Raster graphics is almost universally used today
-For PC's, images encoded in vector graphic format are sometimes used
+for both PCs and text terminals.  For PC's, images encoded in vector
-but they are translated to raster graphics format for display (with a
+graphic format are sometimes used but they are translated to raster
-drop in image quality).
+graphics format for display (with a drop in image quality).
 
-<sect2> Full Graphics Terminals (often known by other names) 
+<sect1>  Thin Clients (Terminals ?)
-<p> None of these are covered in this document.  A terminal that
+
-deserves to be called smart is a graphics terminal which can rapidly
+<sect2> Introduction 
-display full-screen graphics just like a PC monitor.  It will also
+<p> These are thin (minimal) computers that behave something like
-have a mouse.  Bytes sent to it often represent bit-maps for pictures
+terminals.  Since text terminals (except for very old one) run an
-(and other graphics).  It will often use a high-speed connection to
+embedded operating system, they are also like a computer.
-its host computer using twisted pair or coax cable.  X-Window
+Thin-clients need more computing power.  In contrast to text-terminals
-terminals are such devices.  See the link to Xterminal-HOWTO at <ref
+thin clients all display a modern high-speed GUI.  They are dependent on
-id="related_howtos" name="Related HOWTO's">.  So are some "thin
+more powerful computers (servers) for their operation.  For a true
-clients" including ones which have a MS-Windows GUI which comes from a
+terminal, the computing work and disk storage will all be done on the
-remote Windows Terminal Server.
+server.  At the other extreme, most of this work and storage is done
+at the client but some things such as administration, still depend on
+the server.  Since such a client is not really "thin" it's a misnomer
+to call it a "thin client".  Some claim that text-terminals are also
+thin clients but they are not really since they don't conform to the
+client-server model.
+
+Thus a thin client is like a terminal and perhaps should be called a
+terminal.  The thin client has a GUI with a mouse that makes it
+seem like you are using a computer.  You are, but that computer may be
+far away and have many other people using it at the same time you are.
+Communication is over a high speed network cable, often twisted pair
+(UTP).  Some thin clients can in addition emulate a text terminal and
+have a serial port connector for that purpose.  One even has a USB
+interface.
+
+There are two major types of thin clients (and some additional types as
+well which will not be discussed here).  One type is the "Window
+Terminal" which usually runs under MS software and servers.  The other
+type is the "network computer" which is supposed to be platform
+neutral.  This implies they should work with both MS Windows and Linux
+but early models may not be easy to use with Linux.
+
+<sect2> Window Terminals
+<p> These can run under MS Windows NT/2000 using a proprietary protocol.
+They are true terminals since all the computing work is done by the
+server running Windows.  They are also called "Window-based Terminals"
+(WBT).  Some have support for unix-like systems as well and may not
+claim to be WBTs (even though they can be used as WBTs).  They are
+something like computers since they run an operating system (often
+stored in flash memory so it may be updated).  Some can support
+X-Windows also and can be used for Linux (from a Linux server).  Many
+so called "network computers" can also run X-Windows.  This will be
+discussed in the next section.
 
 For displaying the MS-Windows GUI, Citrix was (and is) a major player
 with what was called Winterm using it's WinFrame software (which
 supported Windows 3.1).  Microsoft licensed some of this and then came
 out with Hydra (code name), also known as "Windows Terminal Server".
 It works with versions 4 or higher of MS Windows NT.  Then other
-companies that had their own proprietary systems decided to support
+companies that had their own proprietary systems for MS Windows
-Microsoft's system.
+decided to support Microsoft's system.
 
 Citrix uses its ICA protocol and has created an add-on to Hydra known
 as pICAsso so that WinFrame (ICA) based terminals can use the Hydra
-system.  There exits a Linux ICA client.  Microsoft has substituted
+system.  There exits a ICA client that internally runs Linux (but
-RDP (Remote Desktop Protocol) for ICA.  Citrix has replaced WinFrame
+connects to a MS Window's server).  Microsoft has substituted RDP
-with MetaFrame which supports Windows 95 and is used in conjunction
+(Remote Desktop Protocol) for ICA.  Citrix has replaced WinFrame with
-with "Windows NT Terminal Server Edition".  There is also the
+MetaFrame which supports Windows 95, etc. and is used in conjunction
-"MultiConsole Personal Terminal" by Unbounded Technologies.  Tektronix
+with "Windows NT Terminal Server Edition".
-had its own multi-user interface but will now support Hydra.
 
 The above is sometimes called "network computing" since the terminals
 and servers connect to each other over a network.  Network computers
-are something different as described below.
+may be somewhat different as described below.
 
 <sect2> Network Computers (NCs)
-<p>These are neither true computers nor terminals but are something
+<p>These are neither true computers nor true terminals but are
-in-between.  They are also a type of thin client.  One type of network
+something in-between.  One type of network computer (NC's) is a
-computer (NC's) is a computer with a CPU but no hard Disk.  They are
+computer with a CPU but no hard Disk.  The OS it needs to run is sent
-full-graphics and connect to a server computer.  They are different
+to it over a network.  NCs are full-graphics and use the services of a
-from terminals since the programs they run execute on their own CPU
+server computer.  They are a little different from terminals since
-chips.  Java code may be sent to them for execution.  IBM calls this a
+some of the programs they run may execute on their own CPU chips.
-"Network Station".  They should work on IP networks and might work
+Running a browser was supposed to be one of their primary functions
-under a server running Linux.  Wintel established a "NetPC" which,
+and thus Java code applets may be sent to them for execution.  Many
-unlike the above, is almost a PC computer.  However, it has no
+NCs support X-Windows so that one may use a Linux server to support
-removable disks so users can't install their own software or obtain
+it.  IBM called their NC a "NetStation" but now calls it "NetVista".
-copies of anything.  
+They should work on Intranet type networks and NetVista even runs the
+the Linux OS.  
+
+Wintel came out with a "NetPC" which, unlike the above, is almost a PC
+computer.  However, it has no removable disks so users can't install
+their own software or obtain copies of anything.  
 
 <sect2> Thin Clients Under Linux
 <p> Linux provides NFS (Network File System) so that if ordinary
-computers (not thin clients) are connected to each other via a
+computers are connected to each other via a network, then a person on
-network, then a person on one computer can run programs on another
+one computer can run programs on another computer.  Such a program
-computer.  It works also with X-Windows so that one may see GUI images
+sends messages to you over the network so that it appears just like the
-generated on another computer.  Linux also allows a computer to be
+program was being run by your local computer.   It works also
-diskless (see Diskless-HOWTO) and boot over a network.  Thus using a
+with X-Windows so that one may see GUI images generated on another
-diskless computer which runs NFS is just like using a NC (Network
+computer.  Linux also allows a computer to be diskless (see
+Diskless-HOWTO) and boot over a network.  Thus using a diskless
+computer which runs NFS enables you to run programs on another
+computer (the server).  This is just like using a NC (Network
 Computer).  It's not really a NC but it's emulating a type of NC.
-It's also sometimes referred to (incorrectly ?) as a "terminal".
+It's also often called a "terminal" and in some sense it is.
 
 Thus if you have an old PC with an ethernet card (NIC) you may be able
-to use it as a NC.  Even if it doesn't have a NIC, you could use it as
+to use it as a NC.  The details of this are covered in
-a text-terminal.  See <ref id="term_emulation" name="Terminal
+Thinclient-HOWTO.  Even if your old PC doesn't have a NIC, you could
-Emulation">.  So Linux too supports a type of thin client which is the
+still use it as a text-terminal.  See <ref id="term_emulation"
-subject of Thinclient-HOWTO.  For using the Sun JavaStation NC under
+name="Terminal Emulation">.  
-Linux see the JavaStation-HOWTO.
+
+There are also a number of genuine Network Computers (NC) that will
+work with a Linux server.  Today some NCs run the Linux OS inside the
+NC.  Before Linux became popular, NCs didn't run the Linux OS but
+required some other OS.  But even if the NC needs a non-linux OS, it's
+often possible to make it work with a Linux Server.  The non-linux OS
+is simply stored as files on the Linux Server.  Then when the NC
+starts up it sends a message to the Linux Server asking for the
+non-linux OS files.  This non-linux OS is thus sent to the NC over the
+network and the NC boots.  
+
+The Linux Server runs the NFS and X-Windows both of which must be 
+supported by the NC.  This enables one to use the NC as if it were an
+X-Window terminal.
+
+There are some HOWTOs for certain brands of NCs:
+
+<itemize>
+<item> JavaStation-HOWTO (by Sun)
+<item> NC-HOWTO (IBM NetStation)
+<item> NCD mini-HOWTO (NCD-ThinSTAR)
+<item> NCD-X-Terminal mini-HOWTO
+</itemize>
 
 <sect2> Hardware hookups
 <p> There are 3 different hardware arrangements for thin clients.
@@ -548,23 +607,19 @@ and send e-mail to each other.  It's similar to a local network.
 
 <sect1> Are Text Terminals Obsolete ?
 <p> Text terminals are technologically obsolete because for a slightly
-higher cost of hardware, one could build a smart terminal (with the
+higher cost of hardware, one could build a smarter terminal (with the
 same quality of display).  This wasn't always the case since around
 1980 memory cost thousands of dollars per megabyte.  Today with low
-costs for memory and processors, one could make a text terminal smart
+costs for memory and processors, one could turn a text terminal into a
-for only about a 10% or 20% increase in hardware cost.
+GUI graphic terminal for only about a 10% or 20% increase in hardware
+cost.
 
-The reasons that text terminals are fully obsolete are:
+The reasons that text terminals are not fully obsolete are:
 <itemize>
-<item> There is no satisfactory standard interface for smart graphics
+<item> The resolution of characters on the screen is better on
-terminals that can be used with Linux (but there is for MS Windows).
+monochrome terminals than for monitors in text mode.
-However one can run a diskless PC under Linux on a network where the
-diskless PC is a substitute for a smart graphics terminal.
 <item> Many people don't need full screen graphics.
-<item> Text terminals are low in cost and allegedly take longer to
+<item> Since running a text-terminal (in contrast to a GUI-graphics
-become obsolete, yet can give access to a much newer (and powerful)
-computer.
-<item> Since running a text-terminal (in contrast to a full-graphics
 terminal) doesn't consume much of a modern PC's resources, a large
 number of terminals may be efficiently run from one PC.
 </itemize>
@@ -3426,6 +3481,9 @@ become a serial guru.  Most of the defaults should work OK and some of
 the settings are needed only for certain obsolete dumb terminals made
 in the 1970's.
 
+<tt/stty/ is documented in the man pages with a more detailed account
+in the info pages.  Type <tt>"man stty"</tt> or <tt>"info stty"</tt>.
+
 Whereas <tt/setserial/ only deals with actual serial ports, stty is
 used both for serial ports and for virtual terminals such as the standard
 Linux text interface at a PC monitor.  For the PC monitor, many of the