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Path: utzoo!utcsri!utai!wjr
From: wjr@utai.UUCP (William Rucklidge)
Newsgroups: net.micro.amiga
Subject: Re: Amiga's listening to you.
Message-ID: <819@utai.UUCP>
Date: Tue, 22-Oct-85 14:36:34 EDT
Article-I.D.: utai.819
Posted: Tue Oct 22 14:36:34 1985
Date-Received: Tue, 22-Oct-85 15:42:41 EDT
References: <132@amiga.amiga.UUCP>
Reply-To: wjr@utai.UUCP (William Rucklidge)
Organization: CSRI, University of Toronto
Lines: 35
Summary: 

In article <132@amiga.amiga.UUCP> neil@rocky.UUCP (Neil Katin) writes:
> There is enougth bus bandwidth to support eight low resolution bit
> planes, or four high res planes.  (note that for other reasons the
> amiga does not support more than six bit planes...).  Once you have
> this many planes displaying, there is only bus bandwidth for the cpu
> during the horizontal and vertical blanking periods.
> 
> In "normal" operation, when the workbench screen is being displayed
> (2 high res bit planes), the 68000 can run at full speed if the blitter
> is not running.  If the blitter is running then they share the available
> bandwidth (but the blitter is doing its job faster than the 68000 could
> do the equivalent things...).
> 
> 	Neil Katin
> 	amiga!neil


Hum... this raises some questions. From the block diagram I saw in BYTE,
it seems that the Amiga has a layered bus structure. Does anyone know if
this is in fact the case? This would mean that the processor would only
be slowed down/locked out when it was trying to access the lower 512K
bank, and could run at full speed if it was using other memory, regardless
of what display mode was active or what the blitter was doing... if you
had an external RAM expansion you would be able to run the processor at
full speed almost all the time, since your programs would be in non-
contended memory.

This would be a lovely thing to have... full processor speed and lots
of bit planes and blitter action.

-- 
William Rucklidge			University of Toronto
UUCP	{ihnp4	utzoo	decwrl	uw-beaver}!utcsri!utai!wjr
CSNet	wjr@toronto		BITNET	wjr at utoronto
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