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From: toddpw@tybalt.caltech.edu (Todd P. Whitesel)
Newsgroups: comp.sys.apple2
Subject: Re: Virtual Realities ( was Re: 3200 pics )
Message-ID: <1990Aug14.003226.5733@laguna.ccsf.caltech.edu>
Date: 14 Aug 90 00:32:26 GMT
References: <1839@mountn.dec.com> <12275@sdcc6.ucsd.edu>
Sender: news@laguna.ccsf.caltech.edu
Organization: California Institute of Technology
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jonah@amos.ucsd.edu (Jonah Stich) writes:

>excellent software, sp things are actually looking up. Supposedly they're
>going to make the Visionary capable of digitizing REAL TIME 30 fps!! Of course,
>the memory needed for that might be a bit prohibitive, but it's a neat thought!

Well... that depends. I was planning to build such a project, and know exactly
how it can be done. However, TI turned out to be far less generous than I
planned, and the chips the project depends on (the Video RAMs) cost more than
my meager budget allowed. I had to drop the class, but I still have much of the
setup, and later this summer I intend to get at least the analog section
working. The analog section (90% donated by Signetics -- thank you!) is
eventually going to digitize 12 bits (4096 colors raw, no restrictions!) at
any dot clock I give it (up to 22 mhz, the maximum for the digitizers) and
redisplay the digitized picture IN REAL TIME. Frame grabbing is performed by
using video RAMs to take a snapshot of one frame's worth of video. A full NTSC
frame (interlaced, 1/30th of a second) at a dot clock of 14 mhz (80 colums or
Double Hi-res uses that) would produce a picture slightly under 768x512 pixels
and would take about 768K to store. The last price Quoted to me by Texas
Instruments for this much VRAM was six 44c251's at $40 each or $240. They
probably cost less now and they might even be willing to sample them (a few
months ago they were so new you couldn't even sample them!).

I'd like to know more about these people. Where are they (LA area so I can
visit them during school?) and what is their phone number?

Todd Whitesel
toddpw @ tybalt.caltech.edu