Re: 68008 co-processor board complete working design available ...

[Jim Gilbert <brokerjim@gmail.com>]

On Nov 9, 7:00 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:
> On 11/9/2010 3:43 PM, Jim Gilbert wrote:
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> > On Nov 8, 7:57 pm, "Michael J. Mahon"<mjma...@aol.com>  wrote:
> >> On 11/8/2010 2:32 PM, Jim Gilbert wrote:
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> >>> Back in 1985-1987 I implemented a 68008 wirewrapped co-processor board
> >>> that ran on both my Apple II+ and my Apple IIGs.  (I never tested in
> >>> on a IIe.)
>
> >>> This design was based on a Motorola design note and featured some
> >>> considerable extensions:
>
> >>> 8 Mhz 68008
> >>> 128 K DRAM (Intel 64x4 FPM DRAMs)
> >>> 2732 EPROM
> >>> Communication with Apple II back plane via a dedicated read port and a
> >>> dedicated write port, each attached to a Mostek 4501
> >>> 256 x 8 FIFO.  These FIFOs enabled both processors to speak to the
> >>> other with relative impunity since they handled timing issues well.
> >>> 68901 MFP chip serving as interrupt controller, parallel ports, serial
> >>> port (complete with full modem control), and timers for 68008.
> >>> Hardwired reset pushbutton on top edge of card.
> >>> Software:
> >>> (1)  PROM Monitor on 68008 initialized everything, maintained software
> >>> refresh of DRAM, and implemented bidirectional communications protocol
> >>> with host 6502 (read/write a byte/word/long/block, run code beginning
> >>> at x, reset).
> >>> (2) Applesoft debugging monitor on 6502 which helped load and debug
> >>> code on the 68k
> >>> (3) RAM Disk software used to test 68008 where the co-processor was
> >>> just used as RAM drive for the 6502
> >>> (4) Print spooler for the 68008 using its memory to spool for the 6502
> >>> (not sure I still have this)
>
> >>> I have a working wirewrapped board, block diagrams, schematics, wire
> >>> lists, theory of operation, construction and debugging guides, timing
> >>> diagrams, the works...
>
> >>> I built this out of parts that were mainly free samples from Motorola,
> >>> Intel, Mostek etc. back when I worked for a system company.
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> >>> I used to actually sell the kit on Usenet but unfortunately the key
> >>> single component that became unavailable was Hollywood Hardware's
> >>> wonderful full-length Apple II prototyping board which I used.  To run
> >>> the card in an Apple II GS I had to use a bus extender because the GS
> >>> case is a little shorter front to back than the IIe or II+ ones
> >>> were.
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> >>> I am seriously thinking of scanning and loading all this stuff into a
> >>> web site and making it public domain if anyone is interested.
> >>> As far as I can tell the 68008 and the 68901 and the 4501s are still
> >>> all available.  The rest of it is all 74 series TTL except for one 555
> >>> timer chip.
>
> >>> My design, was heavily influenced and inspired by the Motorola design
> >>> note but is clearly significantly different and original.
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> >>> The main problem with building another one or more would be finding a
> >>> viable Apple II prototyping board that is big enough.
>
> >>> The 68008 software is assembly language in the AT&T syntax that was
> >>> accepted by the BSD UNIX system at work and the public domain 68K
> >>> assembler for CP/M I used on my Z/80 coprocessor (Softcard, then
> >>> Applicard).  Yes, the 68008 co-existed with the Z/80 cards...
>
> >>> I no longer have an Apple II.  In order to build or play with one of
> >>> these a bus extender is very valuable because you'll wear out your
> >>> backplane slot with too many insertions and extractions otherwise...
>
> >> Jim, I'd be very interested in your design.  It is considerably more
> >> capable than the 68008 card I acquired several years ago!  That card
> >> had a single 8-bit port, with handshaking--pretty slow communication.
>
> >> I think it would be a great idea to scan in the documentation and make
> >> it available on the web.
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> >http://jgg-apple2-68008.110mb.com
>
> > Here's the web site.  Currently there is a photo of the board on the
> > home page, a link to a page with the conceptual block diagram, a link
> > to a page with the Programmer's Reference Manual, and a link to a page
> > with the Conceptual Theory of Operations.
>
> > This is just the beginning of the technical information available.
>
> Wow--I see you really *used* that long proto board!  ;-)
>
> -michael
>
> NadaNet 3.1 for Apple II parallel computing!
> Home page:  http://home.comcast.net/~mjmahon/
>
> "The wastebasket is our most important design
> tool--and it's seriously underused."

I have now uploaded the Motorola Application Note AN896 by Geoff Brown
which inspired this design. This material is copyright 1984, Motorola.