From: mark@taylor.uucp (Mark A. Davis) Subject: Re: X terminals: Suggestion for projects like SLS, MCC, etc. Date: Sun, 20 Jun 1993 05:23:33 GMT
ben@rex.uokhsc.edu (Benjamin Z. Goldsteen) writes:
>mark@taylor.uucp (Mark A. Davis) writes:
>>>>We could come up with all kinds of numbers depending on what the requirements
>>>>are. I have a flexible configuration to support a wide variety of displays.
>>>>This cuts costs.
>>> Hmm -- 100 $1500 PC's versus 90 text terminals? I can not even
>>>find a 286 anymore -- the cheapest PC's I can find are 386SX-33's. They
>>>are much faster than a text terminal at text work, and they can do
>>>graphics (at $400/dumb terminal, you are not doing graphics).
>>Faster in what regard? They can display information faster? Not true on
>>a moden text terminal. If the users don't need graphics, then why spend
>>lots more money and worry about more upkeep? That was part of the point.
> I believe you mentioned serial ports -- I would have to assume that
>you are not connecting to your server at more than 38,400 baud (and
>9,600 is more likely). The scrolling and response over a serial line
>just does not compare to, say, WordPerfect running under DOS on a 286 or
>386.
We are not comparing a terminal display speed to software running locally
on a clone. It is a comparison, of sorts, to remotely displayed information.
In this case, they seem to be, generally the same speed (but this too, can
vary wildly depending on ports, which software, which terminals, etc).
> There is a lot more work involved for one -- you have to encode
>and decode the signals (I assume you are using ANSI standard terminals
>like VT420's or something?. Everytime I hit a letter, the computer has
>to drop to bottom of the screen and update the status line. That
>happens pretty damn quick on a PC, but I do not see that happening as
>quickly on a dumb terminal.
Then you have not looked at the Wyse 160... :)
It seems to keep up with 38400 baud with little flow control. Much better
than the older terminals.
>You also run into those wonderful keyboard
>incompatibilities (unless you restrict yourself to a pretty limited set
>of keys). My point here was that you can not compare a $400 dumb
>terminal to a $1500 PC -- they do not provide the same level of
>capabilities
The keyboard is never a problem. Pick the one you want.
Yes you can compare them, as long as one compares them both as terminals :)
>>That is not true. In a multi-user multi-tasking environment not everyone is
>>using the power of the host as the same split second. So when load is normal,
>>or light, each user has access to most of the power of a fast host. During
>>heavy loads the multiple CPU's kick in. During very heavy loads is the
>>only time things start to degrade some. But this is rare if the host is
>>carefully configured. (At least here it is)
> 100 PC's provide about 1500 (very distributed) SPEC's. I gave a
>factor of 10 for multitasking. I thought that was fair -- I accidently
>deleted the section where I said this could be achieved through multiple
>processors. As for access to most of the power of a fast host...it is
>wonderful to see JPEG decompression or Zip 1.9 compress on our
>RS/6000... However, there are limits of how fast a machine can be --
>I/O limits, lock problems, task-switching, etc -- a lot of that is OS
>related, though.
Too true.
> Assuming that you are complete computerized and that people are
>actually using the computer to do their work (unlike what most people
>spend there time doing in most GUI's -- customizing their colors), what
>would you consider a fairer factor? Right now, I have a 386SX-20 in
>front of me emulating a VT220 (although very poorly...and the damn thing
>has started dropping characters for no good reason...) -- it does not
>take much of a computer to do this...
Correct, a 386sx with amber screen, keyboard, very small hd (or eeprom your
term program), fast serial port, misc. Hard to come up with such a machine
that can be quality and in the $350 - $400 range. But it can be a good
comparison.
>On the other hand, assume our
>users are running word processors, databases, spreadsheets, or various
>other personal productivity applications (perhaps e-mail, DTP, graphic
>design, etc).
But we run word processors, databases, preadsheets and graphics preview stuff
on Wy160's...
>Last of all, it
>seems like there is some duplication. My experience with X terminals is
>that you need 4 or more MB left over after the server is loaded
That is not normally true. The Tek server and overhead takes up about
1.5MB of the standard 4. This leaves 2.5 MB available. I have run all kinds
of thisngs, like WP, Island, Asterx, etc... and the closest I ever came to
running out of memory on it was about 900k. I guess this can vary depending
on the applications (otherwise why would it be upgradable to 12MB?)
> -- and
>you might want some swap too so that windows do not get killed as the
>terminals tries to keep itself afloat (which then contributes to network
>traffic).
EEEK!!! On a central host arragement, swapping is not allowed! If you swap,
this can be very yucky. I would never recommend that. Install as much RAM
as needed to prevent swapping. (We currently have 96MB of RAM. I did budget
to go to 128 if necessary for this coming fiscal year).
>If you have a fair amount of fonts, you could see an X
>terminal with 10 MB crash, if you do not have swap, after a few
>applications attack it (I have).
I have not seen this, and I have run some pretty font intensive stuff on a
4 MB Xterminal...
>>>For this solution to beat the cost of the PC
>>>solution, we have average less than $600/X terminal or $60,000.
>>Perhaps there, but not here. Like I said, the numbers can vary wildly
>>depending on what your objectives are and what the environment is like.
> I am not sure how this could not be true -- your X server costs
>$900. The PC you quoted cost $1,500. For the hardware to come out
>cheaper (which is what you quoted), the cost of the host and the
>terminals must cost less then the cost of PC's.
That is not necessarily true. Especially since almost all Unix networks are
still going to have a major "file server" somewhere. Let's assume that
a file server is necessary. That alone could cost at least $10,000. But I
hate to assume anything about a system for which the needs are not known.
> Now, you can argue that
>you get different things (e.g. UPS).
True, which brings me back to the environment thinggy....
>>Can't really address that. Don't have enough experience with using
>>ethernet for non-data purposes. I suppose it could be a problem. But I
>>don't find any flooding of the ethernet. Although there will be a lot of
>>activity, it is very small and often. With distributed systems (especially
>>diskless) the activity is less frequent, but there is a lot more info
>>being transfered (files, meaning more collisions).
> I am not much of a fan of diskless. Dataless is as far as I think
>it should go (and that is not bad - we have a couple of dataless DG
>AViiON workstations -- they feed off the main DG AViiON server -- binary
>compatible so we do not have to have things like bin.aviion, bin.hp,
>etc).
I'm not terribly either. It would seem that in most cases either separate
diskful computers or terminals or a combination is best.
> I am a little confused why fileserving a PC requires more of the
>network then display serving an X terminal. The PC asks for nice large
>blocks (though, all at once...). The X terminal will have to send over
>the same information as little packets as well as all these little
>packets sayings things like, "he moved the cursor."
But the X packets for Xterminals are very tiny. If you are comparing it to
a workstation concept.... then look at a big database inquiry. Just two
from workstations could totally flood the ethernet for a long time. This
is often the case in a distributed business system, because the important
(and/or big) files are on a "file server". In many cases, it would be a
lot less load overall to just run the stuff on the file server. But, now
if you are doing that, then you are using the workstation as a terminal
in a centralized arrangement.
> I could see a
>definite win for small edits (open document, delete line 75, save,
>quit), but otherwise, I do not see why the X terminal is so much more
>efficient.
It can be, as long as it isn't being used for heavy graphics run off a
central host. In those cases, a "workstation" concept is probably more
appropriate. Otherwise, they do fine.
>BTW, which X terminals have microphones or A/D converters??
NCD has models now. Tek is working on it. DOn't know about others, but
there are a LOT of Xterminal manufactuers. A list is periodically posted
in comp.windows.x
>Apple is coming out with some nice things where they integrate various
>multimedia into your computer such that it could say do your voice-mail?
>I am not quite sure what extensions there are for X to handle sound, but
>I imagine X11R6 is going to have multimedia extensions?
Eeek... I guess we will soon have to listen to email as well as the phone :)
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