Jeff Kell writes:

> This is a left-field question, but there's quite a diversity of readers
>  on the list...
>
>  We have a hands-on PC training lab set up with the typical "less than
>  ideal" projection equipment.  The room is too small to get an adequately
>  sized image projected and be "readable" other than for PowerPoint
>  slides.  We are trying to demonstrate terminal sessions in a lab with
>  12 "student" stations and one instructor's PC.

I don't know if you're interested in a very low tech/ very low cost solution,
but it is what we do in our training classes, and we've found it to work very
well for us. We simply use a serial (not LAN) connection composed of three
wires (send/pin 2, receive/pin 3, and ground/pin 7 on a DB-25 connector),
running from the instructor's terminal/PC to the DTC. When using a terminal
emulator (and many forms of client software), all keys struck on the
instructor's keyboard are transmitted out on Pin 2 to the HP3000 where they
are immediately echoed back to the terminal/PC on Pin 3 and recorded by the
client software/emulator on the instructor's CRT screen.

When the HP3000 is in a full duplex mode, as it almost always is when using
serial communications, the data coming back contains not only the instructor's
keystrokes but also the HP3000's responses. Thus, that information can be very
easily distributed to all of the other PCs/terminals by simply running pins 3
& 7 (receive and ground) as a parallel bus to all of the other devices. When
this is done, all of the slave PCs/terminals will repeat exactly what the
master PC/terminal is displaying.

If there are any caveats to this arrangement, they are simple: first, the
slowest PC/terminal (if you have a mix of devices) must be the master
(instructor's) machine because all flow control information will emanate from
that device, not the slaves. Indeed, the slaves won't have any capacity to
transmit information at all to the HP3000, if you use the simplest wiring
harness possible. Second, the method won't work well if your screens are forms
mode/block mode screens. Communication in this circumstance is half-duplex, so
both sides of the conversation can't easily be simultaneously shown. But
character mode screens (which is completely true in our situation) work like a
champ.

We have tried projection systems in the past, but this simple method of
distributing information produces much clearer screens that are much less
tiring to read for the individuals sitting through training -- and it can all
be done in a brightly lit room.

Wirt Atmar