Re: Stellation Mill 6809 card clone / FPGA

[rjustice@removeme.internode.on.net]

This web site has some better pictures:
http://www.hackzapple.com/ORG1/M2/COPROC/6809MILL.HTM
(you can click on the zoom button)

/Rob

On Mon, 12 Jan 2009 16:52:47 -0800 (PST), MdntTrain <js@cimmeri.com>
wrote:

>
>{conversation moved from "Not your father's Applicard"}
>
>Alex, Steven, I'd be very interested, and a committed buyer, for a
>re-
>creation of "The Mill" -- the 6809 board for the Apple II.   I don't
>have one but here's a pic and little blurb on it:
>http://www.vintagemacworld.com/8bit.html
>
>What is the 6809 specific operating system claimed available for the
>Apple II?!
>
>~ JS
>
>=====================
>Steve Hirsh replies:
>
>MdntTrain wrote:
>> Alex, Steven, I'd be very interested, and a committed buyer, for a re-
>> creation of "The Mill" -- the 6809 board for the Apple II.   I don't
>> have one but here's a pic and little blurb on it:
>> http://www.vintagemacworld.com/8bit.html
>
>That would be more correctly: s/Alex, Steven/Alex/ :-).  He's the
>man.  I'm a
>software guy with enough digital hardware knowledge to be dangerous
>(now,
>analog audio systems are another story, but who uses them anymore?).
>
>> What is the 6809 specific operating system claimed available for the
>> Apple II?!
>
>I'm guess it's Microware OS-9.  I've started working with that
>environment on
>my Tandy CoCo and it's a lot of fun.
>
>Every once in a while a Stellation Mill will pop up on eBay, but they
>always
>go for ridiculous amounts.  The nice thing about Alex's upcoming FPGA
>project
>board is that you can implement the 6809 (or, better yet, 6309) in
>synthesizable logic and have enough room left over for two or three
>more CPUs.
>
>There are FPGA designs for the 6809 out there already for the
>picking.  The
>real chips are getting difficult to find and the 6309 just about
>impossible.
>Not like the 6502 and Z80, I'm afraid.
>
>Steve
>
>=====================
>David Wilson replies:
>
>> What is the 6809 specific operating system claimed available for the
>> Apple II?!
>
>Yes - it was Microware OS-9 (I have that for my Mill card -
>unfortunately it never worked on my IIe but did work on a II+ at
>work...).
>
>=====================
>Steven H replies:
>
>> Yes - it was Microware OS-9 (I have that for my Mill card -
>> unfortunately it never worked on my IIe but did work on a II+ at
>> work...).
>
>Oh good.  Can you make the OS distribution available for posterity in
>case
>someone (me) wants to try cobbling up a 6809 on an FPGA?
>
>=====================
>JS replies:
>
>> The nice thing about Alex's upcoming FPGA project
>> board is that you can implement the 6809 (or, better yet, 6309) in
>> synthesizable logic and have enough room left over for two or three more CPUs.
>
>You mean YOU could implement it.   I wouldn't have the foggiest idea
>of how to put a CPU core on an FPGA, much less the entire Mill card.
>I'd like to learn, but man, what a stretch.  My brain is back at 7400
>series.
>
>How about this idea.   If Alex introduces his FPGA kit, what about a
>group effort / learning project to recreate the Mill on his card?
>All in the group would commit to purchasing Alex's card, then we'd
>all
>help each other learn about it and make kinda like an Open Source
>project of getting a Mill, docs, and software all organized.   A
>project like this would help legacy brains like mine learn about the
>newer technologies.. it'd be a great thing that'd go beyond just a
>Mill card... especially if enough people would get on board.
>
>
>Course, I think it'd be even cooler to do a 68008 and CPM 68k, but
>the
>Mill -- if we can find the Apple II software for it -- is definitely
>esoteric enough.
>
>
> JS
>
>=====================
>Steven H replies:
>
>> You mean YOU could implement it.   I wouldn't have the foggiest idea
>> of how to put a CPU core on an FPGA, much less the entire Mill card.
>> I'd like to learn, but man, what a stretch.  My brain is back at 7400
>> series.
>
>Don't get me wrong!  I'm not anywhere NEAR far enough on the learning
>curve to
>code a CPU in VHDL.  But, I think sewing together modules written and
>tested
>by others isn't beyond my grasp.  I've been spending a lot of time
>reading
>through every book I can get my hands on, rewinding all the way back
>to the
>fundamentals of Karnaugh maps and by-hand logic minimization.  I
>actually knew
>this stuff reasonably well when I got my CS degree, but never worked
>in the
>hardware domain and it sort of dissipated.
>
>> How about this idea.   If Alex introduces his FPGA kit, what about a
>> group effort / learning project to recreate the Mill on his card?
>> All in the group would commit to purchasing Alex's card, then we'd all
>> help each other learn about it and make kinda like an Open Source
>> project of getting a Mill, docs, and software all organized.   A
>> project like this would help legacy brains like mine learn about the
>> newer technologies.. it'd be a great thing that'd go beyond just a
>> Mill card... especially if enough people would get on board.
>
>
>I'm always up for a challenge, so why not?  The first order of
>business is to
>find some architectural information on the 6809 Mill.  The second is
>to
>reverse engineer the little piggy-back board that made it possible to
>run OS-9
>on the Apple.  If the implementation is anything like the CoCo (a good
>bet),
>memory re-mapping is a requirement.  Everything in OS-9 is fully
>relocatable
>and it dynamically maps logical <---> physical address space in 4k
>chunks.  My
>CoCo has 512K installed and it's able to use all of that by swapping
>these
>chunks into the 64k address space as needed by the currently running
>task.
>Task switching is triggered by a hardware timer interrupt.  Quite
>sophisticated for a little machine.
>
>The 6809 architecture is not really very similar to the 6502, and is
>highly
>optimized for relocatable, PC-relative addressing.
>
>> Course, I think it'd be even cooler to do a 68008 and CPM 68k, but the
>> Mill -- if we can find the Apple II software for it -- is definitely
>> esoteric enough.
>
>If your interests run in that direction, I believe there are designs
>out there
>for 68k cores also.
>
>Steve
>
>=====================
>David W replies:
>
>> I'm always up for a challenge, so why not?  The first order of business is to
>> find some architectural information on the 6809 Mill.
>
>Not a problem - the circuit diagram is published in the documentation
>that came with it.
>
>
>> The second is to
>> reverse engineer the little piggy-back board that made it possible to run OS-9
>> on the Apple.
>
>No problem there either - I built my own to enable switching between
>OS-9 and non-OS-9 modes via software instead of needing to take the
>lid off and flick the little switch. The card is just a simple 4 bit
>in 4 bit out to remap the upper bits of the address bus. Without the
>board, the Mill has two address mappings:
>
>0xxx..Fxxx => 0xxx.Fxxx (straight through)
>0xxx..7xxx,8xxx..Fxxx => 8xxx..Fxxx,0xxx..7xxx (invert A15)
>
>The daughter board remaps the 16 4KB banks in a similar fashion to
>the
>Z80 card giving OS-9 a larger contiguous address space than either of
>the original mappings.
>
>
>>  My
>> CoCo has 512K installed and it's able to use all of that by swapping these
>> chunks into the 64k address space as needed by the currently running task.
>> Task switching is triggered by a hardware timer interrupt.  Quite
>> sophisticated for a little machine.
>
>The Mill OS-9 is only Level 1 so does not support more than 64KB. The
>timer interrupt is not available on a standard Apple II so I think it
>fakes it somehow.
>
>=====================
>Michael Mahon replies:
>
>Of course, like all 68* machines, it's big-endian, so data exchange
>with
>a 65* machine is a bit of a pain...
>
>-michael
>
>=====================
>Steve in Australia replies:
>
>6809's and 6309 were very popular with apple clones towards the end
>of
>the Apple era. Many clones had all three processors - 6502, Z80 and
>6809 on a single main board.
>
>http://www.applelogic.org:88/AL/ACCORD.JPG
>
>The adoptor I designed will allow as many processors you need to be
>brought into an Apple II via peripheral cards, which includes
>Hitachi's 63C09's and its hidden powerful instruction set.
>
>http://www.applelogic.org/AL/6809+65C816hires.JPG
>
>steve
>
>=====================
>JS replies:
>
>> 6809's and 6309 were very popular with apple clones towards the end of
>> the Apple era.
>
>They were?  Why is that?
>
>> http://www.applelogic.org:88/AL/ACCORD.JPG
>
>
>** This link didn't work for me.
>
>> The adoptor I designed will allow as many processors you need to be
>> brought into an Apple II via peripheral cards, which includes
>> Hitachi's 63C09's and its hidden powerful instruction set.
>
>> http://www.applelogic.org/AL/6809+65C816hires.JPG
>
>Steve, what the heck is this a picture of??   And tell us more about
>this "adoptor"?
>
>JS
>
>=====================
>A2Retro replies:
>
>> ** This link didn't work for me.
>
>Remove the port number 88 from the url
>
>=====================
>David W replies:
>
>> Is the Mill similar to the PCPI card in that it's a full computer
>> running with the Apple II as a terminal host?    What would the Mill
>> have been typically purchased for?
>
>
>No, it is closer to a Microsoft Soft Card - no on-board RAM. The 6502
>only gets to run during 6809 dead cycles.
>
>The Mill was available in 3 software configurations.
>
>
>1) 6809 Assembler - runs under DOS 3.3
>2) OS-9
>3) Apple Pascal Speed Up - offloads math computations to the 6809
>(not
>sure as I never had this one).
>
>=====================
>Alex Freed replies:
>
>> Hehe.. well, likely the first is to wait for Alex to be on board with
>> all this.. as without his projects, it's a no-go.
>
>
>
>The upcoming Carte Blanche will be a perfect platform to implement
>it. There are too many Apple related projects in my pipeline that I
>doubt I'll want to make a special project for it.
>I've *heared* that 6809 was a wonderful CPU but never used it in
>any form.
>
>There exists an FPGA implementation of a 6809 system easy to port
>to any FPGA. Some years ago I did build it for an old Spartan 3
>board from Digilent ($99) but didn't know what to do with it :)
>
>
>If someone posts a pointer to the board schematics I'll tell you
>how easy it will be to clone.
>
>
>-Alex.
>
>=====================
>JS replies:
>
>JS send schematics to Alex.