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From: beilke@puff.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: Reactions to IBM PC2 graphics
Message-ID: <621@puff.WISC.EDU>
Date: Wed, 8-Apr-87 13:17:45 EST
Article-I.D.: puff.621
Posted: Wed Apr  8 13:17:45 1987
Date-Received: Sat, 11-Apr-87 09:12:54 EST
References: <10726@topaz.RUTGERS.EDU> <1582@husc6.UUCP> <713@dragon.tc.fluke.COM>
Organization: U of Wisconsin CS Dept
Lines: 46
Keywords: VGA Killer graphics

In article <713@dragon.tc.fluke.COM>, kurt@tc.fluke.COM (Kurt Guntheroth) writes:
> Wait a minute.  The VGA is supposed to do 256 colors at once.  Is that
> perhaps done in sort of the same way the Amiga does 4096 colors at once?  If
  No.  The Amiga uses Hold-And-Modify, where you can can the palette
  on the raster line, giving you all colors possible on screen at on time,
  with only 6 bit planes.
  The IBM on the other hand does not have this capability, and therefore
  have to use the same approach as the Mac II.  (i.e., 1 bit plane
  for 2 colors, 2 bps=4 colors, ..., 8 bps=256 colors.
> all 256 colors may be assigned to any pixel, in any order, and in a way that
> allows access to the screen in an ordinary way, then they have something.
> But think about it, 256 colors.  They obviously aren't doing 256 bit planes.
  Look above.
> Nobody can do that; you would need gigabits/second of bus bandwidth.  Maybe
> one byte per pixel?  A 640x480 window in this mode would use 370Kbytes.  I
  Now you're talking.  2^8=256 colors in 320 by 480, and 2^4=16 colors
  in 640 by 480.  A 'set' amount of display memory means that 
  for twice the resolution, with same number of bits available, you
  have to split the 8 bits up, to 4 for each new pixel.  And go back
  to only 16 colors.
> also don't see how a gate array of 12,000 gates complexity could compete
> with a full-custom video chip.  (What is the complexity of the Amiga video
> chip?  Anyone know?)  Does the PCII have a blitter?  Copper?  Is the VGA
> even organized in a way that makes these things possible?
  1) Can't say right off hand.
  2) No.
  3) No.
  4) I doubt it very much.
   
>
> By the way, the Amiga 2000 is still CHEAPER than the PCII/30, their bottom-
> of-the-line product.  Phthththhpt!  It is also faster in every performance
> parameter.

  Well, hope this helped...


             -         -  - ---> Matt Beilke <--- -  -       -
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