Re: Projectors for Symbolics consoles

[TYSON@ai.sri.com (Mabry Tyson)]

    Date: Thu, 4 Apr 91 10:04 PST
    From: delisio@pwtc.tc.pw.com (Jefferson DeLisio)



     Henry Mendenhall asked -
  
      What's the latest and greatest projector capable of handling Symbolics
      monochrome output? 

    Forget latest and greatest, could someone enlighten those wallowing in 
    ignorance as to what class of projectors we are talking about in general
    and how one goes about using them with the Symbolics monitor and what
    other information one might need to know - costs, results, etc. in
    considering preparation for large demos.

    thanks,
     Jeff DeLisio 

Our projection set up uses a Sony VPH 1042Q projector with lenses that
give us a 100" diagonal.  That's takes RGB or composite or S-VHS and is
only about $6.5K.  We drive it with the output from a Lyon-Lamb Real
Time Scan Coverter which runs $23.7.  The scan converter takes RGB of
various flavors (we've used Suns (RGB), Symbolics (Cad-Buffer (II?)),
and TMC connection-machine as inputs) and converts it to the standard
NTSC RGB that the projector takes.  We also use it for driving video
tape recorders.  Two things about the Lyon-Lamb:  you can pan, scroll, or
zoom it (so you can focus into the area of interest) and you can control
it by computer (RS232 or RS422).

The output of the Sony is quite good.  You *can* read a "normal" sized font
on a Sun (1Mpixel) screen when the whole screen is projected, but just
barely.  The brightness is excellent.  The controls are such that you can
project from a table, a ceiling, rear-project it, etc.  There must be 60
or so convergence controls inside the machine.  We've been using it as a
table projector but have just now installed it in a permanent place where
it is being used as a rear projector.

The Lyon-Lamb has been adequate but we don't know of a better product
for us.  The way we have had it set up was that we'd wire the various
machines into the 3 sets of inputs.  For instance, we have one system
that uses two screens on a single Sun.  The Sun is set up so when the
mouse moves from one screen to another, the program on the Sun sends out
(via the net) a request to switch to input B on the scan converter.  I
have a server (on a Symbolics, of course) that gets the request and
sends the right code down the serial line between the Symbolics and the
scan converter.  

Also attached to the Symbolics is a serial mouse (as in IBM-PC, I had to
use one with its own power cord because of the distances involved).  This
is used by a person giving a demo to pan, scroll, zoom, or switch inputs.

I also have code to have Symbolics machines to talk over the net to the
scan converter server so they can programmatically control the projection.

The only complaints I have about the scan converter are
1. Its price.
2. It glitches a bit when you change things (eg, pan & scroll simultaneously)
3. Sometimes (rarely) it gets hung up, and you need to power cycle the 
scan converter.


There are single board scan converters for Suns at a much cheaper price but
I don't think they allow zooming (etc).  That's quite necessary for what we
do.