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From: dca@toylnd.UUCP (David C. Albrecht)
Newsgroups: comp.sys.amiga.hardware
Subject: Improving the Custom chips
Message-ID: <336@toylnd.UUCP>
Date: 6 Apr 91 07:58:38 GMT
Lines: 28

My problem with Commodore's non-improvement of the custom chips is not
with their limitations in the A500 and A2000 class machines but rather
that they are still the same in the A3000 class machines.  Realistically,
most of the operations the blitter can do are better done by the 68030
in the 3000.  As Commodore has not demonstrated any ability to vastly
improve their custom chips I would say it's time to move to solutions
which lessen their dependence on said chips.  As processors get faster
the situation will only get worse.  While sticking all these functions
in custom chips have economic reasons I think given the way they seem
frozen in stone it might make better sense to use a little more off the
shelf external chips.  Use the external RAMDAC
that has built-in aliasing which is being incorporated in some PC VGA
boards rather than waste chip real estate on the weenie RAMDAC we
currently have.  My impression was that this RAMDAC chip can give an apparent
resolution increase without a corresponding video memory size penalty.
Eliminate the blitter functions entirely and instead have
the memory write which invokes the blitter interrupt the main processor
and have it do the blitter functions.  Use the increased real estate and
RAMDAC performance this gives you to support more and better video modes.  Keep
the copper but hopefully use the space from the eliminated blitter/RAMDAC
(I don't remember if these are even in the same chip with the copper) to make
it support faster bus speeds.  Maybe even go with external 16 bit D/As for sound
(use the same ones in the CDTV?).
Admittedly these will increase the complexity and cost of the 3000
motherboard but frankly that the 3000 runs a chip set of essentially the same
speed and capability of the 1000 is a crime.

David Albrecht