diff --git a/LDP/howto/linuxdoc/Text-Terminal-HOWTO.sgml b/LDP/howto/linuxdoc/Text-Terminal-HOWTO.sgml index 11b0cecd..a8767b45 100644 --- a/LDP/howto/linuxdoc/Text-Terminal-HOWTO.sgml +++ b/LDP/howto/linuxdoc/Text-Terminal-HOWTO.sgml @@ -1,11 +1,14 @@
- Text-Terminal-HOWTO + 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 -is: Thin Clients; some broken url's changed or -deleted. +version your are currently reading is: v1.16, October 2000 . New in this version +is: Thin-clients+; NC Howtos; Correction of bad typo "text +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 -olden days "video display unit" (VDU) was used for terminals but -strictly speaking, it excludes the keyboard. +terminal", "video terminal" and "video display terminal" (VDT) and +"green terminal" (since many used green displays). In olden days +"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. -For PC's, images encoded in vector graphic format are sometimes used -but they are translated to raster graphics format for display (with a -drop in image quality). +rare and expensive. Raster graphics is almost universally used today +for both PCs and text terminals. For PC's, images encoded in vector +graphic format are sometimes used but they are translated to raster +graphics format for display (with a drop in image quality). -<sect2> Full Graphics Terminals (often known by other names) -<p> None of these are covered in this document. A terminal that -deserves to be called smart is a graphics terminal which can rapidly -display full-screen graphics just like a PC monitor. It will also -have a mouse. Bytes sent to it often represent bit-maps for pictures -(and other graphics). It will often use a high-speed connection to -its host computer using twisted pair or coax cable. X-Window -terminals are such devices. See the link to Xterminal-HOWTO at <ref -id="related_howtos" name="Related HOWTO's">. So are some "thin -clients" including ones which have a MS-Windows GUI which comes from a -remote Windows Terminal Server. +<sect1> Thin Clients (Terminals ?) + +<sect2> Introduction +<p> These are thin (minimal) computers that behave something like +terminals. Since text terminals (except for very old one) run an +embedded operating system, they are also like a computer. +Thin-clients need more computing power. In contrast to text-terminals +thin clients all display a modern high-speed GUI. They are dependent on +more powerful 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 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 -Microsoft's system. +companies that had their own proprietary systems for MS Windows +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 -RDP (Remote Desktop Protocol) for ICA. Citrix has replaced WinFrame -with MetaFrame which supports Windows 95 and is used in conjunction -with "Windows NT Terminal Server Edition". There is also the -"MultiConsole Personal Terminal" by Unbounded Technologies. Tektronix -had its own multi-user interface but will now support Hydra. +system. There exits a ICA client that internally runs Linux (but +connects to a MS Window's server). Microsoft has substituted RDP +(Remote Desktop Protocol) for ICA. Citrix has replaced WinFrame with +MetaFrame which supports Windows 95, etc. and is used in conjunction +with "Windows NT Terminal Server Edition". 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 -in-between. They are also a type of thin client. One type of network -computer (NC's) is a computer with a CPU but no hard Disk. They are -full-graphics and connect to a server computer. They are different -from terminals since the programs they run execute on their own CPU -chips. Java code may be sent to them for execution. IBM calls this a -"Network Station". They should work on IP networks and might work -under a server running Linux. Wintel established 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. +<p>These are neither true computers nor true terminals but are +something in-between. One type of network computer (NC's) is a +computer with a CPU but no hard Disk. The OS it needs to run is sent +to it over a network. NCs are full-graphics and use the services of a +server computer. They are a little different from terminals since +some of the programs they run may execute on their own CPU chips. +Running a browser was supposed to be one of their primary functions +and thus Java code applets may be sent to them for execution. Many +NCs support X-Windows so that one may use a Linux server to support +it. IBM called their NC a "NetStation" but now calls it "NetVista". +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 -network, then a person on one computer can run programs on another -computer. It works also with X-Windows so that one may see GUI images -generated on another 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 is just like using a NC (Network +computers are connected to each other via a network, then a person on +one computer can run programs on another computer. Such a program +sends messages to you over the network so that it appears just like the +program was being run by your local computer. It works also +with X-Windows so that one may see GUI images generated on another +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 -a text-terminal. See <ref id="term_emulation" name="Terminal -Emulation">. So Linux too supports a type of thin client which is the -subject of Thinclient-HOWTO. For using the Sun JavaStation NC under -Linux see the JavaStation-HOWTO. +to use it as a NC. The details of this are covered in +Thinclient-HOWTO. Even if your old PC doesn't have a NIC, you could +still use it as a text-terminal. See <ref id="term_emulation" +name="Terminal Emulation">. + +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 -for only about a 10% or 20% increase in hardware cost. +costs for memory and processors, one could turn a text terminal into a +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 -terminals that can be used with Linux (but there is for MS Windows). -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> The resolution of characters on the screen is better on +monochrome terminals than for monitors in text mode. <item> Many people don't need full screen graphics. -<item> Text terminals are low in cost and allegedly take longer to -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 +<item> Since running a text-terminal (in contrast to a GUI-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