From: xappeal@xtreme.sublink.org (X Appeal Info)
Newsgroups: comp.windows.x
Subject: Re: PCs/Macs as Xterminals - any advice?
Date: 4 Sep 92 00:15:30 GMT
Organization: Xtreme s.a.s. - Livorno, Italy

moc@bnl.gov (Mike O'Connor) writes:

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

That can be true, but in many cases the needed components are already there:
users who already have an Ethernet connection used for character-based Unix
access can easily upgrade to X.

> 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.

If you have a network of PCs (Novell, PC-NFS or other), it's easy to put
the X server software on a file server, and "centrally administer" it, by
using a BOOTP server to assign the variable parameters to each PC.

> 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.

Well, do they sell X servers for PCs, or X terminals? :-)
I think their opinions are somewhat biased towards hardware...

> 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.

What is a "computer-intensive environment"?
In any case, the performance level which allows a practical use of X servers
is better judged by real users.

> 	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.
> 	As mentioned before, the answer lies in cost and performance.
> 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.

The average professional PC is today something with at least a 386 CPU,
and SuperVGA capabilities (at least 800x600 with 256 colors on a 512KB card)
are becoming standard also for low-cost no-name machines.

>  	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.

Unless you buy some X server with built-in TCP network software. And in
any case not all X servers are so expensive. To make an example, an
academic institution could pay $200 per seat for a 10-user license of
our product.  And the extra cost for the network card is rarely needed;
usually PC users interested to install X on their PCs already use character
based TCP/IP software via Ethernet.

> 	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.

Things are rapidly changing, see above.

> 	High-resolution 14-inch monitor			$1,100

That's about twice as much of common street prices!

> 	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.

I think that DOS TCP/IP software manufacturers do not agree at all! :-)

> 	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.

Probably *some*, definitely not *all*!!!

> 	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.

May be, may be not. It depends on the used applications and the speed
of the X server.

> 	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

Although many X terminals are faster, performances over 5000 Xstones are
generally useful for most applications. In any case the threshold is very
subjective and users have to do their choices based on a cost-performance
evaluation. Which for an installed base of powerful networked PCs can be
definitely better than the X terminal solution.



Best Regards

Giovanni Novelli
Xtreme s.a.s. - Livorno, Italy
xappeal@xtreme.sublink.org
Newsgroups: comp.windows.x