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

[Jim Gilbert <brokerjim@gmail.com>]

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.)
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> > This design was based on a Motorola design note and featured some
> > considerable extensions:
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> > 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)
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> > I have a working wirewrapped board, block diagrams, schematics, wire
> > lists, theory of operation, construction and debugging guides, timing
> > diagrams, the works...
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> > 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.
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> > 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.
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> > 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...
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> > 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.
>
> -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."

Huzzah,  someone is interested enough to at least read this.  I will
start with the high level, overview, block diagram etc.