21602MR@MSU.BITNET (Mark Rosenberg) (03/10/89)
I'm working on a research project using a MAC II w/ a touch screen to present stimuli to pigeons who then peck the screen. The problem I'd like to solve is having a dual display - take the video signal from the Mac II and send it to a box where there are two video outs on the other side which I can run one to the touch screen and the other to an observation room. Right now, the only screen output we get is to a Skinner box. (have you ever tried debugging stuff from inside a Skinner box ?) Is there an electronics firm around that would build this type of device ? Mark Rosenberg < 21602MR@MSU.BITNET > Psychology Department - Animal Cognition Michigan State University
trebor@biar.UUCP (Robert J Woodhead) (03/12/89)
In article <5521602MR@MSU> 21602MR@MSU.BITNET (Mark Rosenberg) writes: >I'm working on a research project using a MAC II w/ a touch screen to present >stimuli to pigeons who then peck the screen. The problem I'd like to solve >is having a dual display - take the video signal from the Mac II and send it >to a box where there are two video outs on the other side which I can run one >to the touch screen and the other to an observation room. If I understand you correctly, what you really want is to be able to get standard video out of a Mac II so you can pump it into any number of tv monitors (and even record it on tape). There are several video boards that will do this, and can also overlay the digital images on live or taped video. Mass Microsystems has a board called the Colorspace II that does a very nice job; it can overlay 640x480x 256 colors onto an existing video signal (if desired) and then outputs a NTSC standard video signal that can be sent to any TV set. Otherwise, you will have to get a splitter box (which may have to do some amplification and other techie hooha [Im a software person]) and both the monitors you use will have to be capable of accepting the Mac II color signal (eg:they will have to be Mac II monitors). These are expensive, though not as expensive as the Colorspace II, which you can probably get for around $1750, perhaps less. However, the extra capabilities of boards like this make them well worth the price; you can do a lot with them. -- * Robert J Woodhead * The true meaning of life is cunningly encrypted and * * uunet!biar!trebor * hidden somewhere in this signature... * * Biar Games, Inc. * ...no, go back and look again *
poynton@vector.Sun.COM (Charles Poynton) (03/13/89)
In article <5521602MR@MSU>, Mark Rosenberg <21602MR@MSU.BITNET> indicates
that he would like video from a Mac II to be displayed identically on two
monitors.
The box that he wants is called a "video distribution amplifier", known in
video as a DA but I won't call it a DA in THIS newsgroup. A distribution
amplifier has a single set of video input connectors (e.g. R, G, B, sync)
from one source device, and multiple sets of output connectors, one set for
each of a number of destination devices. A distribution amplifier contains
amplifiers to drive multiple 75 ohm loads without the attenuation that would
result from "T" connectors. Distribution amplifiers are essentially
independent of scan rates etc., but one needs an appropriate "bandwidth".
For Mac II 640-by-480, 60 Hz video, 10JMHz should be sufficient. Buy one of
these from an industrial A/V company.
Most industrial 525-line TV equipment is provided with "loop-through"
connectors, and one simply daisy-chains the signal through successive pieces
of equipment without the necessity of a distribution amplifier. But loop-
through connections are not common in computers. If you were willing to
modify the monitor's electronics you could accomplish the same thing, but I
presume you don't have access to analog hardware expertise.
I don't believe that overlay capability as suggested in <5521602MR@MSU> is
necessary. Also, dropping down to 30 Hz frame rate as in NTSC is not
necessarily appropriate for pigeons . Does anyone know their flicker
sensitivity?
Charles Poynton <poynton@sun.com>
Sun Microsystems, Inc. 415-336-7846