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From: jesup@cbmvax.commodore.com (Randell Jesup)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: a3000 questions...
Message-ID: <21915@cbmvax.commodore.com>
Date: 25 May 91 01:41:48 GMT
References: <3860@ux.acs.umn.edu> <1991May8.162146.24619@sbcs.sunysb.edu> <21863@cbmvax.commodore.com>
Reply-To: jesup@cbmvax.commodore.com (Randell Jesup)
Organization: Commodore, West Chester, PA
Lines: 44


	Peter corrected me on a few points regarding the deinterlacer and
interlaced productivity/superhires screens.  What do I know about hardware
anyways?  ;-)

In article <21863@cbmvax.commodore.com> jesup@cbmvax.commodore.com (Randell Jesup) writes:
>>>4] Even with the multiscan monitor, both SuperHiRes-Interlace and
>>>  Productivity-Interlace flicker heavily, and SuperHiRes looses a lot
>>
>>  This could be the type of interface connection between the monitor and the
>>Amiga.
>
>	Of course.  The internal de-interlacer can't deal with more
>than ~700 pixels horizontal or ~500 vertical (NTSC).  The modes you tried
>were ~1280x400 and ~640x960.  The de-interlacer cuts out, so you get
>straight interlaced video to the monitor.  Interlaced video flickers.

The display enhancer cuts out from Productivity-Interlaced, but it's
not smart enough to detect superhires-interlaced.  It will de-interlace
superhires-interlaced, but it will only sample every second pixel.
If 1280x400 is flickering with the de-interlacer off, it's because
the sampling is happening on the rough edge between 35 ns pixels.
You have to manually turn off the de-interlacer to use SuperHires and
SuperHires-Lace properly.

>>  With the higher resolutions, some verticle columns disappear on our
>>system as well, so I think it is unavoidable with the current graphics
>>output. Either that or my a3000 is mesed up too. :)
>
>	The monitor doesn't have the pixel resolution to handle it.  1280x200/
>400 is meant for getting finer edge resolution for things like character
>generation for video, ot really for general use (too imbalanced, and most
>monitors won't allow showing all pixels).

	Many monitors can handle far more than 640 horizontal, including the
A1950.  The missing columns are being missed by the sampling of the
de-interlacer.  Whether the monitor can actually display 1280 horizontal
depends on the hardware/mask/dot-pitch in the monitor.

-- 
Randell Jesup, Jack-of-quite-a-few-trades, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com  BIX: rjesup  
Disclaimer: Nothing I say is anything other than my personal opinion.
"No matter where you go, there you are."  - Buckaroo Banzai