Apple ][ 32-bit coprocessor using MC68020/MC68881 (historical)

[Eric Smith <eric-no-spam-for-me@brouhaha.com>]

In 1985, shortly after they were first announced, I ordered an MC68020
32-bit microprocessor and an MC68881 floating point coprocessor.  I was
quoted a pretty long lead time and fairly high prices.  But the parts
actually arrived very quickly, and I hadn't yet completed the design of
the system they were intended for.  I wanted to test the chips quickly,
so I needed to kludge something up in a hurry.

Previously, Rich Ottosen had designed and constructed two Apple ][
coprocessor cards using the MC68008, which is a version of the 68000
with an 8-bit bus.  One card used static RAM, and the other used
dynamic.  A debug monitor was stored in EPROM on the card.  Loren Blaney
had modified the XPL0 compiler to produce native 68K code instead of the
I2L interpreted code (like P-code) normally used on the Apple.

Since there was already a small software base in existence, I designed a
similar card to use the MC68020 and MC68881, running at the blazing
spped of 7 MHz, with 8K bytes of EPROM and 32K bytes of static RAM.

The software for the MC68008 card worked with very little change.  Loren
Blaney modified the XPL0 compiler to produce native MC68881 code for the
floating point.

Unfortunately a few years later I disassembled the card.  I don't have
any photos, but two years ago I was looking through my files and found
a photocopy of the hand-drawn schematic, and put it on a web page.

In February 1986 I redrew the schematic in MacDraw.  I no longer have
the file, but last week I found a printed copy, so I've just scanned that
and put it on my web page as well.

I can scan listings of some of the other software we ran if anyone
is interested.

The URL is:

    http://www.brouhaha.com/~eric/retrocomputing/apple/apple2/68020/

Information about the XPL0 language, including binaries and source code
for the Amiga and PC versions, is available from Loren Blaney's web
site:

    http://www.idcomm.com/personal/lorenblaney/