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From: agodwin@acorn.co.uk (Adrian Godwin)
Newsgroups: comp.sys.3b1
Subject: Re: Hardware freaks Unite (on this one)
Keywords: 3B1, cache, hardware project suggestion.
Message-ID: <6386@acorn.co.uk>
Date: 15 Apr 91 13:22:05 GMT
References: <95@fbits.ttank.com> <1991Mar26.023948.3966@i88.isc.com>
Organization: Acorn Computers Ltd, Cambridge, UK
Lines: 28

In article <1991Mar26.023948.3966@i88.isc.com> botton@i88.isc.com (Brian D. Botton) writes:
>  Motorola has an app note that describes how to make a daughter board for
>the 68020 to replace a 68000 or 68010, you can also have a 68881/2.  I would
>dearly love to make this board, including support for vidpal, but I haven't
>had the time.  I just don't have time to do both the kernel mods and the
>hardware.
>  BTW, the 68020 does have an instruction cache and the app note claims ~ 100%
>increase in performance.  If anyone who has access to the code would like to
>colaberate I would like the help.

A number of companies sell daughter boards - some of them based on the Motorola
app. note - as an upgrade for the Commodore Amiga. It seems to generally held that
they only manage about a 40% performance increase UNLESS they're also fitted with
32-bit memory - otherwise, the use of the '020 in 16-bit mode severely limits
its performance. 

However, since most of these boards directly replace the Amiga's 68pin DIP 68000,
and are intended to fit inside the limited space available inside an A500, they 
may be useable on the 3b1. This would at least reduce the problem to the
software part and would provide, in addition, a cheap memory upgrade path.

Apologies if the thought of putting an Amiga upgrade inside your 3b1 offends you :-).

-adrian

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Adrian Godwin                                        (agodwin@acorn.co.uk)