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From: stever@videovax.UUCP (Steven E. Rice, P.E.)
Newsgroups: net.micro.amiga
Subject: Re: LIFE on a 68020 (Re: Tom)
Message-ID: <1971@videovax.UUCP>
Date: Wed, 1-Oct-86 11:56:24 EDT
Article-I.D.: videovax.1971
Posted: Wed Oct  1 11:56:24 1986
Date-Received: Sat, 4-Oct-86 09:48:16 EDT
References: <8609221813.AA04648@cory.Berkeley.EDU> <1137@hoptoad.uucp>
Reply-To: stever@videovax.UUCP (Steven E. Rice, P.E.)
Organization: Tektronix, Comm Group, TV R&D
Lines: 30

In article <1137@hoptoad.uucp>, John Gilmore (gnu@hoptoad.uucp) writes:

> In article <8609221813.AA04648@cory.Berkeley.EDU>, dillon@CORY.BERKELEY.EDU (Matt Dillon) writes:
>> 	With its cache, a 68020 doing simple blits would use most of bandwidth
>> (100% for simple copies).  Since a 68020 usually has a faster clock than a
>> 68000, it would easily beat out the Amiga's blitter.   Additionaly, you
>> wouldn't need multiple blitter passes.
>> 	Of course, the disadvantage is that it uses the processor... the system
>> would basically stop while you're doing the blit.  But hell, you only live
>> once.
> 
> It doesn't really matter whether the CPU is doing it or the blitter is
> doing it -- if ANYBODY is burning up 100% of the memory bandwidth, the
> system will "basically stop" -- or stop doing anything but the blit.

The advantage of having the 68020 perform the data movement is that it can
process the data as it streams through.  Thus, if data is to be processed
for display in a system with a blitter, the processor picks it up, massages
it, and puts it into memory, from whence the blitter picks it up and moves
it to its destination.  Using the processor to process and blit, the data
needs to be picked up and put down only once.

Of course, the ideal system would have dual- (multi- ?) ported memory with
a 68020 for processing and a 68020 for display control (drool, drool,
drool. . .).

					Steve Rice

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