From: moc@bnl.gov (Mike O'Connor)
Subject: Re: PCs/Macs as Xterminals - any advice?
Reply-To: moc@bnl.gov
Organization: Brookhaven National Laboratory
Date: Tue, 1 Sep 1992 17:40:50 GMT


>We are upgrading our computer systems lab and are thinking
>of getting Xterminals.

If you are networked via ethernet, buy X terminals

>We have an NCD Xterminal at the moment which is really nice.
>But for the same price we can get two 486 PCs or a Macintosh
>Quadra running X emulation software.

When you add up all of the extra components from all of the different vendors
you soon find out that the apparent cost savings is just not there.

The more terminals you need the more the scales tip toward X terminals.
X terminals can be centrally administered, after initial setup ALL administration
on an NCD terminal can be from a remote location and centralized modifications
get distributed to all terminals.  PC's must each be put together and administered
seperately, and PCNFS is not as robust as NFS on a true UNIX host.

You will spend a great deal of time just getting all of the PC Xterminal pieces
to work together, and if the PC doesn't work who do you call?

I don't work for any hardware or software vendors, my opinions come from extensive
X terminal experience and administrator of them.

The following is a paper contributed by Tektronix reguarding the question of 
PC based X terminal emulators.


-------------------------------------------------------------------------------
Mike O'Connor			            |
Computing and Communications Division	    |  
Brookhaven National Laboratory	Bldg. 515   |   "Mothers don't let your
Upton NY 11973				    |    PC's grow up to be     
INTERNET: 	moc@bnl.gov                 |    X terminals"
PHONE:  	(516) 282-7410              |    
FAX:    	(516) 282-7688              |
-------------------------------------------------------------------------------




			Inexpensive X Window Seating:
		      X TERMINALS OR X SERVERS ON PCs?

		   A Network Displays Division White Paper

				    by 
			      Jim Thomassen

				May 1992

For More Information:			Tektronix, Inc.
Phone: 1-800-225-5434			Network Displays Division
PAX: (503) 682-4948			26600 S.W. Parkway Ave., M/S 60-787
email: tekxpress@orca.wv.tek.com	May 1992

11W-7381
Copyright 1992, Tektronix, Inc.,	X Terminals or X Servers on PCs?


			INEXPENSIVE X WINDOW SEATING:
		      X TERMINALS OR X SERVERS ON PCs?

	A white paper by:
	  Jim Thomassen, product marketing manager
	    Tektronix Network Displays Division

	A low-cost X Windows network can be built either of two ways:
with a dedicated X terminal or with a DOS or Windows 3.0-based personal
computer.  Usually, the decision comes down to cost and performance.
	In order to make the right choice, you need to know the true
cost of each solution and have a complete understanding of the products'
performance.  To analyze cost, you should calculate all of the different
price-tags involved, including upgrade needs and administrative
expenses.  To measure performance, you should consider ease of use,
reliability and maintainability.
	Several key criteria should be used to evaluate the two options.
For instance, it has been universally accepted that X servers on PCs are
primarily meant for casual X users.  Yet, it is unlikely the performance
level or this type of configuration will be sufficient enough to
compete with dedicated X devices, like X terminals, in a
computer-intensive environment.
	However, the obvious advantage the PC-based X servers have over
X terminals is that companies can maintain their installed base of PCs
as they move toward distributed processing.
	Companies with an established network of powerful PCs, with a
need for only moderate X performance, should consider a PC X server
solution.  Other candidates are companies which will not or can not give
up local PC processing and are willing to upgrade existing PCs in order
to gain acceptable X Window performance.

Current X Server Market

	Before trying to choose between PC or X terminal alternatives,
you should first understand today's X server market.  For example, there
are four essential ways to turn a PC into an X terminal:

	1. X server on DOS-based PCs
	2. X server on MS Windows-based PCs
	3. Full X Window system on DOS-based PCs
	4. Full X Window System on UNIX-based PCs
	Since the fourth option is really considered a workstation, it
will be excluded form the following summary.

X Server on DOS-based PCs

	The first truly successful implementation of X on PCs was X
server software, or X Window terminal emulation software, running on
DOS-based PCs.  Essentially, these software-based products allow a PC
to become an X terminal, thereby gaining the ability to control a
workstation running X Window software.  
	DOS-based X server products currently make up the largest share
of the market.  This is primarily due to timing, since MS Windows was not 
a viable PC interface unitl 1990.  These types of products operate in a 
straight DOS environment and require the least amount of memory.
	When measured by Xstones, DOS-based server products are
considered faster than MS Windows versions.  They are also the least
expensive to purchase.  Like all of the product variations discussed,
you'll need an Ethernet card and Ethernet software to turn DOS-based PCs
into X terminals.

X Server on MS Windows-based PCs

	Since a vast majority of PC users ar moving to MS Windows, this
solution is expected to gain the largest share of market growth over the
next few years.
	The primary advantage of this route is the ability to display an
X Window session on the PC's screen concurrently with DOS sessions.
Plus, you can usually cut and paste between X Windows and DOS.
	Given the nature of MS Windows, any graphics hardware solution
supported by MS Windows will also be supported by the X server software.
This is important when you're considering some of the high resolution
graphic solutions available today.

X Window System on DOS-based PC

	A new product from Quarterdeck, called DeskviewX is a DOS-based
operating system that allows a PC to function as an X Window server,
plus run X Window client applications and DOS applications
simultaneously.
	The big advantage DeskviewX has over the other X server
solutions is that it allows an X terminal to connect to and control a
DOS-based PC running DeskviewX and thereby, control character-based DOS
application from the X terminal.  DeskviewX is a true multitasking
DOS-based operating system which allows a PC to become an integral part
of an existing UNIX networking environment.

The Hidden Cost of PC-Based X Servers

	Now, the question remains, "When does PC-based X make sense, and
when would a low-cost X terminal be a better solution?"
	As mentioned before, the answer lies in cost and performance.
When you consider the true cost of a PC alternative, it may be a less
viable option when compared to an X terminal network.  And, a PC-based X
server might fall short of your organization's performance needs.
	To determine the whole cost of a PC-based X Windows option, you
need to ask three important questions:

1. 	Does your company plan to upgrade its installed PC base?

	If so, does  the PC base consist of 286,386 or 486 systems?
Keep in mind, to get reasonable performance, a PC will need to be a
386/20 MHz or more -- unless the required X performance is remarkably
low, like 4K stones.
	If the system is running MS Windows, PCs will need a minimum of
2 MBytes of RAM or 3 MBytes of RAM to display four or more windows with
a Windows manager.

2. 	Are the PCs networked and is the network a running TCP/IP?

	If not, it will cost about $750 or more per PC for a network
card and TCP/IP software.  An additional $500 should be added for X
server software, resulting in a $1,250 investment per seat.
	Even if your PCs are networked with Novell or other PC-based
networks, you would still have to purchase TCP/IP software.  This costs
between $300 and $500.  Total investment would be an extra $800 or
$1,000 for the Xserver.

3. 	What type of display devices are currently used?

	The display capabilities of most installed PCs are usually no
higher than EGA or VGA with 16 colors and 600 x 400 resolution.  This
may not be adequate for displaying multiple X Windows.  Costs for
upgrading with an accelerated graphics package for PCs, range from
$1,200 to $1,500, depending on the card and monitor.

	In summary, if you're planning to use PCs as X terminals, the
approximate investment would be:

	Hardware/Technology				Cost
	386-based PC					$2,400
	Accelerated graphics card			$695
	with 256 colors
	High-resolution 14-inch monitor			$1,100
	Network card					$250
	Network software				$500
	X server for PC					$500
--------------------------------------------------------------------------
	Total						$5,445

	In addition to cost, you must also look carefully at
performance capabilities, particularly those related to networking,
graphics and the PC's dependence on the network.

Network Issues

	In a recent customer survey of DOS-based X Windows server
produced by the X Business Group, one of the primary problem areas for
PC-based X server users was the installation and maintenance of PC-based
TCP/IP network software.
	Today's TCP/IP network software for personal computers is not as
robust as workstation or X terminal network software, so routers,
bridges and other types of network hardware may yield poor performance,
if in fact they work at all.
	Lacking plug and play capability, TCP/IP is difficult to install
on PCs.  Due to the diverse PC community, monitoring and maintaining the
reliability of PCs running over a TCP/IP network can also be
challenging.

Network Dependence

	Networked PCs running X Windows are extremely dependent on the
network and network software.  All TCP/IP software for PCs limits the
number of windows that can be accessed at one time.  some network
software packages require 14 multiple windows just to start up, this
presents an immediate problem.

Graphics Considerations

	PCs were not initially designed to handle multiple window
graphics.  Therefore, if you're planning to use computer-intensive
graphics like rotating filled images, the PC's display capabilities may
pose a problem.
	Unassisted graphics cards of any resolution and color depend
upon the PC for power.  If you install a high-resolution, 256-color VGA
card, the performance may be unacceptable for X Windows operations.
	Finally, the small PC screen size may also be hindering, since
systems with 12-inch displays limit the number of windows users can
access at once.

System Administration Considerations

	Every time you introduce a new variable to the PC network,
there's a risk that the previously running software and hardware will
become dysfunctional.  This tends to be especially true in more
complicated networked environments. 
	A new RAM card, for instance, can completely shutdown a PC-based
X server because it may not be supported in a particular configuration,
blocking the X server software's ability to access memory.  While
upgrades and enhancements might be valuable to individual users, they
can be a system administrator's nightmare.  PC users are notorious for
"personalizing" their PCs with hardware and software.
	The final point for users to consider when choosing between PCs
and X terminals is the performance of X servers on PCs.  The X bench
ratings range from a slow 3.5K Xstones to 33K Xstones.  The breakdown is
a follows:

	o Without accelerated graphics -- approximately 3.5K-6K Xstones

	o With co-processor graphics -- as high as 18K Xstones

	o With 8514 graphics/486-based PC -- as high as 32K Xstones
	  not running Windows 3.1
	
Conclusion:
	A DOS-based or MS Windows-based PC with sufficient power and
accelerated graphics can be successfully used with a X Window server in
a somewhat casual environment.  The cost of obtaining an adequate level
of power, adding graphics and connectivity, as well as the increased
administrative issues, are the major factors to consider when deciding
whether upgrading a PC to X is a viable option.

Copyright 1992, Tektronix, Inc.,


	

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