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From: breemen@rulcvx.LeidenUniv.nl (E. van Breemen)
Newsgroups: comp.sys.amiga.hardware
Subject: Custom Chips
Message-ID: <1991Apr9.091806.21523@rulway.LeidenUniv.nl>
Date: 9 Apr 91 09:18:06 GMT
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Organization: Leiden University, the Netherlands.
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There has been a lot of talk about the speed of the Custom chips
in the Amiga. It is clear that the Custom chips are currently slowing
down the Amiga. I am developing a accelerator board myself and I know
that such a board has to synchronize to the original 7 Mhz machine, because
the Amiga makes (too much in my opinion) assumptions about the signals in
different clock cycles. The best thing to do is to split up the Amiga in
to parts: 1) the calculation part with a 68030 on say 25/33 Mhz and 
          2) make a seperate part with all the slow stuff like video
             io and sound at 7/14 Mhz.

In this way you can use (almost) twice as much buscycles for the video
part and the 68030 can run at full speed. In the video part, you can put
a 68000 or 68020 or even a customized graphicschip (i.e improved blitter).
The basic communication should be done by graphics.library (as supported
by Commodore). So good software (which doesn't poke in the screen) will
work directly. Software like games, can make use of the 68000 in the
video part for direct manipulation of video ram.
By separating the boards, one board is not slowed down by the other if
we doesn't speak of the software demands. In this way the Amiga can be
given more computing power by making a faster calculation board.
All these idea's are currently implemented by the Accelerator boards but
they are just a kind of a hardware patch. The Amiga isn't ( in my humble
opinion ) designed for upgrading. Just look at all the problems with
noise, dma etc. 
I hope people will see this as a positive contribution to the Amiga
Future.

Erwin van Breemen
Orega Holland.