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From: davids@ucscf.UCSC.EDU (Dave Schreiber)
Newsgroups: comp.sys.mac.misc
Subject: Re: Surely A Iifx Blows An Amiga 3
Message-ID: <8350@darkstar.ucsc.edu>
Date: 31 Oct 90 06:25:08 GMT
References: <7876.271B9F29@fidogate.FIDONET.ORG> <1990Oct23.193646.8067@usenet.ins.cwru.edu> <1990Oct30.171538.14327@imax.com>
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In article <1990Oct30.171538.14327@imax.com> dave@imax.com (Dave Martindale) writes:

[...]

>It is not possible to provide "workstation" quality in screen images
>while using NTSC-standard (actually EIA RS-170A) video timing.  Amiga chose
>to use RS-170 timing, and so it fits in the low-cost video world very well.
>The Mac family chose to be a workstation, with video suitable for that world.

Wait a minute, I think you changed definitions of 'video' between the third
and fourth line :-).  If your goal is to produce NTSC output, then you need
interlacing.  There's no such thing as "low-cost" video vs. "workstation"
video (at least in the area of timing, which is what you seem to be
implying).  I agree that the Mac is currently better at such things as
1024x768 w/16M colors, but that's not video (your term "screen images"
is a better one).

>As a result of these choices, the Amiga suffers from interlace flicker and the
>Mac doesn't.  I have heard of a device called the FlickerFixer for the Amiga -
>but if it eliminates flicker, it also eliminates NTSC compatibility.

You're assuming that the FlickerFixer affects the entire machine.  Actually,
the FlickerFixer works as a separate entity.  A 15.75Khz video signal
comes in, and a 31.5Khz (scan-doubled or de-interlaced) signal comes
out through a separate port.  In theory, you can hook up your multisync
monitor to the FlickerFixer and your genlock to the regular Amiga video
port and have the best of both worlds (almost;  you won't have the genlocked
video displayable on your multisync, but you should have some NTSC display
deviced hooked into all this along with your VCR anyway).  In practice,
this has not been true because a genlock hooked up to an Amiga alters
the timing of the computer just enough to keep the FlickerFixer from
working.  The makers of the FlickerFixer have produced a $50 hardware
fix for this, and I believe the new Commodore flickerfixer doesn't
suffer from this problem at all.



-- 
Dave Schreiber                                    davids@slugmail.ucsc.edu 
                                or (but not both) davids@ucscb.ucsc.edu
"It was fun learning about logic, but I don't see where or when I will ever
use it again."