Path: utzoo!utgpu!water!watmath!clyde!rutgers!ames!amdcad!sun!pepper!cmcmanis
From: cmcmanis%pepper@Sun.COM (Chuck McManis)
Newsgroups: comp.sys.amiga
Subject: Re: 68000 speed up kits
Message-ID: <41880@sun.uucp>
Date: 14 Feb 88 00:41:16 GMT
References: <6861@agate.BERKELEY.EDU> <3823@cbterra.ATT.COM> <32328R38@PSUVM>
Sender: news@sun.uucp
Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
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Organization: Sun Microsystems, Mountain View
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In article <32328R38@PSUVM> R38@PSUVM.BITNET (aka Marc Rifkin) writes:
>  2. Memory - the '20 is 32-bit; the Amiga is physically (by nature of
>    its PCB) 16 bit (in terms of its busses), so the '20 needs support
>    circuitry to access such memory, and can only take advantage of
>    its speed in 32-bit memory (equals $$).

Technically, this is not true. You see the 68020 has this line that 
tells it what the Bus size is, and it modifies the way it fetches data
internally. The resultant bus accesses look a lot like 68000 bus accesses.
Because the execution time for many of the instructions is one clock faster
on the '020 you should see a slight increase in speed when the '020 is 
running at the identical clock rate of the '000. The cache helps too but
not as much as one would hope. If you double the width of the memory
bus you double it's bandwidth and thus help performance considerably. The
only reason I can think of that some vendors board would run slower than
a 68000 out of 16 bit memory, is that they have broken wait state hardware.
Anyway, it takes no extra hardware. 

--Chuck McManis
uucp: {anywhere}!sun!cmcmanis   BIX: cmcmanis  ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.