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From: pselver@euler.mit.edu (Peter Selverstone)
Newsgroups: comp.sys.amiga.misc
Subject: Re: CBM Support is GREAT!
Message-ID: <1991Mar13.062558.1013@galois.mit.edu>
Date: 13 Mar 91 06:25:58 GMT
References: <1991Mar4.024723.4765@sugar.hackercorp.com> <13397@hubcap.clemson.edu> <19802@cbmvax.commodore.com>
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In article <19802@cbmvax.commodore.com> daveh@cbmvax.commodore.com (Dave Haynie) writes:
>In article <13397@hubcap.clemson.edu> ddyer@hubcap.clemson.edu (Doug Dyer) writes:
>>
>>Hmm.  Does anyone know what C= plans to do about the A3000 problems
>>(specifically the deinterlacer's flickering black line)?  Is this a bug
>>that they will fix or is it a feature? 
>
>Technically speaking, it's a feature.  Converting a full NTSC frame the way
>the A3000's Amber chip does it is just guaranteed to give you that flickering
>1/2 line.  That's an effect of the NTSC standard and the way its different
>frames get displayed.

No Dave, NTSC has nothing to do with it.  Don't believe everything
you hear.  An interlaced field has 262.5 horizontal intervals which
become 525 unique lines at twice frequency.  With a static image
there is no reason for these lines to change.

What is clear from the presence of this artifact and the much more
serious one which is visible when Amber is used with the non-ECS
Denise is that the system was designed on the assumption that it
would be blanked by the monitor bezel.  The A1950 is able to do this,
but it is one of the very few monitors which can.  The "standard"
for all computer displays other than those derived from television
is that the margins are blanked electrically.

A bit more concern for compatibility with third-party hardware
would have avoided both this problem and Amber's other serious problem
of genlock incompatibility.  The A3000 is supposed to move Commodore
into new markets; success in these markets will require some new
attitudes toward standards and compatibility.

> All this long and short, odd and even frame nonsense
>I don't know all that much about.  It might be possible to fix, I don't know
>if they're planning to or not.  It would certainly require a revision of the
>Amber chip to accomplish.
>
>-- 
>Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
>   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
>	"What works for me might work for you"	-Jimmy Buffett
-- 
Peter Selverstone  -  Spy Pond Systems - Arlington, MA  -  (617)648-7468
pselver@euler.mit.edu  bix:pselverstone  PLINK:pselverst  CIS:72527,2652