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From: farren@well.UUCP (Mike Farren)
Newsgroups: net.micro.amiga
Subject: Re: interlace mode
Message-ID: <511@well.UUCP>
Date: Sun, 19-Jan-86 14:13:35 EST
Article-I.D.: well.511
Posted: Sun Jan 19 14:13:35 1986
Date-Received: Tue, 21-Jan-86 08:14:02 EST
References: <570@amiga.amiga.UUCP> <877@h-sc1.UUCP>
Organization: Whole Earth Lectronic Link, Sausalito, CA
Lines: 36

In article <877@h-sc1.UUCP>, breuel@h-sc1.UUCP (thomas breuel) writes:
> |	The trick is to plot a pixel ON and ABOVE the line where the
> |pixel is to be placed. This still results in an effective resolution
> |of 400 lines BUT reduces the flicker to almost zilch. I saw this
> 
> Sure, if you use 640x400 as a 640x200 mode, then you won't see
> any flicker, you won't have any higher resolution either, though,
> and you'll waste a lot of memory.

    This isnt 640X200 mode.  You still have 400 (399, actually) vertical
pixel locations, it's just that each pixel is now 2 lines high instead of
one.  It's the same sort of thing that a lot of machines (specifically
Atari 800 and Apple II) did to avoid horizontal color aliasing when using
a standard NTSC type composite monitor.
 
> WHAT I WOULD LIKE TO KNOW IS: is Commodore/AMIGA planning on
> releasing a version of the AMIGA in which this problem has
> been fixed (e.g. in which the monitor can be run at either
> 60Hz or 70Hz)? Is there a hardware patch that can be applied
> to current machines to solve the problem?

  The necessary fix would be fairly expensive. The biggest reason for the
640 X 200 limitation on each field is to reduce the bandwidth requirements
of the coprocessor and the memory, and to allow the CPU more cycles. 
Maintaining the current hardware capabilities and adding the extra capability
you describe isn't an easy job. (Before I hear anything about the Atari ST
and its 640X400, 70Hz screen, let me remind you that that is a one-bit-per-
pixel monochrome screen.  It's ONLY color option is 320X200.  If you are
willing to accept THAT limitation, then the problem isn't too hard.  If you
want a color screen such as the Amiga's, at a reasonable cost, compromises
have to be made.)

-- 
           Mike Farren
           uucp: {your favorite backbone site}!hplabs!well!farren
           Fido: Sci-Fido, Fidonode 125/84, (415)655-0667