Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!snorkelwacker!apple!cheers!greg
From: greg@cheers.uucp (Greg Onufer)
Newsgroups: comp.sys.m68k
Subject: Re: 68020 to 68010 chip adapter?
Keywords: 68020 68010
Message-ID: <__!%V4#.4668@cheers.uucp>
Date: 9 Aug 90 09:30:19 GMT
References: <107@sean.UUCP>
Reply-To: greg@cheers.uop.edu
Organization: Cheers Bar & Grill
Lines: 26

mka@sean.UUCP (mka) writes:
>Ages ago I heard of an adapter that allows a 68020 chip to be
>inserted into a 68010 socket. Reportedly, the 68020 would then
>run without further fuss. Anyone know about this: where they
>might be obtained and if they work?

Motorola has an Application Note containing the schematics for such an
adapter.  It is relatively simple and also allows use of a
floating-point chip.  The board uses the following:

	1 - MC68020
	1 - MC68881
	4 - PAL16R4A-15
	6 - 4.7K pullup resistors

The Application Note is AN944, "MC68020 and MC68881 Platform Board
for Evaluation in a 16-Bit System".

The drawback is that software which relies on the exception stack
frames must be modified.  I had looked into this a while ago as a
means of speeding up my Sun-2, but determined that since the boot
proms and SunOS would no longer run, it was of no use.  The advantages
are increases of performance up to 200% (in the App Note's
benchmarks). 

Cheers!greg