From: lilleyc@cs.man.ac.uk (Chris Lilley)
Newsgroups: comp.windows.x.pex
Subject: Re: X Terminals with PEX support
Date: 4 Sep 92 20:38:20 GMT
Organization: Dept Computer Science, University of Manchester, U.K.

In article <1483@igd.fhg.de> pfuetz@igd.fhg.de (Matthias Pfuetzner)
writes:

>In article <1992Sep2.014239.9065@newshost.anu.edu.au>
bdb112@rsphy3.anu.edu.au (Boyd Blackwell) writes:

>>Has anyone heard of an X-terminals that support the PEX extensions?
>>(and how do you find out - xdpyinfo sometimes mentions PEX, sometimes not!

>If "xdpyinfo" mentions X3D-PEX, then there is the PEX-extension on that
>specific X-terminal, If it doesn't mention, then there is no such extension.
>Look at the PEX-FAQ just posted to this newsgroup.

That is not always true. It represents what should happen, but ...
some servers falsely report that they support the X3D-PEX extension
when they don't. For example, the VAXstation 4000 VLC and the DEC
VT1200 both do this.

>I know of only one currently available PEX-terminal, the Tektronix XP29P. I
>won't recommend it to anyone but developers. It's awfully slow, when it comes
>to non uniform B-Spline things. 

It is awfully slow at *most* things. Rotating a shaded fill area or
quad mesh, for example. It need not be: it has an MC68030 for general
housekeeping and a Texas 34020 + maths co-pro for graphics. It is my
understanding that it uses an unoptimised version of the PEX SI
(although with the holes filled in - HLHSR and double buffering, for
example.)

>But Tektronix will be offering an followup
>product within the near future which will be much more faster than
the XP29P.

Apparently it uses a MIPS R3000A. Whether it is significantly faster
depends on what sort of graphics engine it uses and how much work they
do on the PEX server software.

>Also SHOgraphics is developing PEX-terminals. I have had the chance to test
>some of their alpha versions. They are REALLY fast!

Is that under non disclosure? If not, *spill the beans* ;-)

I gather that HP are working on a PEX version of the HP 700 X terminal
which is cheap and fast. I gather they are doing PEX for their
workstations too - I am itching to see this run on an HP 730 (NURBS in
hardware ...). These are of course just idle rumours I heard :)

>When it comes to workstations and their support for PEX with their vendor
>specific Xservers I know of IBM (you have to start the Xserver with the option
>"-x pex", look at /usr/bin/X11/README.PEX), DEC (as you mentioned), Evans &
>Sutherlands and all the Workstations/graphic-adapter pairs that are listed in
>the X11R5 release notes with the MIT X11R5 Xserver.

>If you want to really use PEX-terminals put in as much RAM as you
>can!! [...]
>The Tektronix XP29P for example comes with 7 MByte as default. You won't
>be able to even init PEX on a window that is screen large (1280x1024 Pixels in
>8 bit color depth) with the structure store on the server side. 

Perhaps one should point out that RAM on the XP29P is in three parts.
The model we looked at had 7Mbyte for the '030 to play with, 2Mbytes of
screen memory and 16Mbytes for the 34020 to work with.

>This terminal
>will get caught (no warnings, no error messages!) and you will have to turn of
>the power to get it properly working again!! It works, when you init PEX with
>the central structure store on the client side, then there is no problem,
>execpt that you won't get any of the rendering capabilities of the terminal.

We never found that problem, but we never opened a window quite that
big. A 1024 square one worked OK though...

BTW the XP29P monitor is really nice. Pity the display is only 8 bits
deep.

I would also suggest that anyone thinking of using an XP29P in a DEC
environment look carefully at the DECnet performance if this is
important to them (one can of course use TCPIP, except that UCX
doesn't do TFTP so booting or getting fonts can be a problem).

These are of course my opinions only...

--
Chris Lilley
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