Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!psuvax1!rutgers!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.atari.st
Subject: Re: Pictures on the ST (Amiga's side!)
Message-ID: <13062@cbmvax.commodore.com>
Date: 5 Jul 90 19:52:54 GMT
References: <4b28c24a.20b6d@apollo.HP.COM> <196@next.com> <672.26899914@desire.wright.edu> <1990Jul2.071658.16558@math.lsa.umich.edu>
Reply-To: daveh@cbmvax (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 30

In article <1990Jul2.071658.16558@math.lsa.umich.edu> hyc@math.lsa.umich.edu (Howard Chu) writes:

>The trick is pretty obvious, it seems. Just use two screens, and flip the
>physical page on every vertical blank. This effectively doubles the number
>of bits per pixel, and as expected, squares the number of colors that can
>be displayed at once on screen. It also introduces an incredibly annoying
>flicker... But hey, Amigans settle for a megapixel display that updates at
>15 hertz, 30 hertz is a lot better. 

You're confused about the Amiga megapixel display.  While it's true that the
entire display is logically updated at either 10Hz or 15Hz (selectable), the
actual video refresh rate (eg, will it flicker?) is 60Hz in the 1008x800x2
mode, and 50Hz in the 1008x1024x2 mode.  You don't see any flicker on these
displays.  But they're not suitable, in the high resolution modes, for real
time on screen animation.  Not that anyone using a monochrome display is all
that concerned about animation anyway.  The simple case of the mouse pointer
"animation" is handled by "mouse-tracking", where the quadrant or sextant of
the logical screen containing the mouse pointer is updated more often.  Note
that, to the system, the screen looks just like you'd expect a megapixel
screen to look, it's only the actual screen driver that must perform any
special tricks to display on one of these monitors.

>  -- Howard Chu @ University of Michigan
>  ... the glass is always greener on the side ...


-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
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	"I have been given the freedom to do as I see fit" -REM