[Coco] [COCO] Raspberry PI and CoCo Cart

[David Ladd]

Well my idea is is just addressing two FIFI buffer's at the Boisy
Interface/Becker ports and then maybe modify the Drivewire 4 server to
talk via parallel rather than serial using the Raspberry Pi's
interface.  I need to find a parallel FIFO chips that can do this.  I
figured a parallel interface would be a bit faster than serial plus
two FIFO chips would provide at least a good buffer to allow the CoCo
to catch up under OS-9 if other processes are going on between
packets.

Though I don't have a Pi yet and I figured since you have a Pi and
wrote DW4 server that could come up with the required hardware to
combine the Pi into a cart to basically be the CoCo's version of the
Boisy Interface/Becker port.

The only thing I know right now is that anyone who still uses a J&M
Controller with a built in parallel port would have to switch to
another floppy controller since it uses the same address ports.

I still need to do more research into the FIFO chips and if 8bit ones
are made.

I figured using the becker port would make things a bit easier since
NitrOS-9 already has the DW driver for it.  The only thing that would
need to be done is for someone who has rights to update the source
code to the HDBDOS project could update the DW read and write files to
include the becker port and then add to the make file to produce
another HDBDOS image that includes a becker compile of HDBDOS.

On Fri, Oct 5, 2012 at 6:24 PM, Aaron Wolfe <aawolfe at gmail.com> wrote:
> I have been wanting/planning/trying to gather information on a "Pi in
> a Pak" for some time now.
>
> Interfacing via a faster, less CPU intensive DriveWire connection is
> interesting, and maybe that is the limit of what can be done.
> However, I had hoped for something a bit different.  I've talked with
> some experts (or at least they know a heck of
> a lot more about it than I do) and gotten some ideas but maybe the
> list has some too...
>
> It seems like the ideal (and maybe unobtainable) interface would be
> one which can read and write directly to the
> bus lines just like a regular ROM pak or drive controller.  Given this
> ability, one could accurately simulate *any*
> pak or peripheral (or several at a time?).  You could also create new
> peripherals, such as interfaces to the various
> I/O found on the Pi (USB, ethernet, audio/video, etc...).   Way better
> than an embedded DW server imho.
>
> I don't know if its possible or practical, I just know that it would
> be awesome.  From what I've gathered... it might be possible
> but it's not a sure thing.  You have to dance pretty fast to play on
> the bus.  The Pi does have an SPI interface capable of many
> Mb/s throughput (one guy's testing says 16Mbps is a practical limit)
> in addition to several GPIO pins.  John Kent showed me
> a cheap I/O processing chip that was cheap, programmable, had SPI and
> a whole bunch of latches, and could operate in the
> multi Mhz range.  Can they be stuck together into something that can
> participate on the coco bus?  I wouldn't even know how
> to guess, but I'd surely like to find out.  Also interested in
> alternate schemes that provide superior/more direct communication
> than the DW style serial line.
>
> Can the Pi be turned into the ultimate virtual MPI?  $0.01 for your thoughts
>
>
>
>
> On Fri, Oct 5, 2012 at 7:09 PM, David Ladd <drencor at gamepixel.net> wrote:
>> One of the things I was thinking is with the cart side is having two
>> FIFO chips to buffer data between the Raspberry Pi and the CoCo.
>>
>>
>> On Sat, Sep 29, 2012 at 5:58 PM, Aaron Wolfe <aawolfe at gmail.com> wrote:
>>> On Fri, Sep 28, 2012 at 10:42 AM, Brian <briang0671 at sbcglobal.net> wrote:
>>>> On 09/28/2012 12:05 AM, David Ladd wrote:
>>>>>
>>>>> Here is a interesting idea I just had.
>>>>>
>>>>> What if we were to interface a Raspberry PI and have it connected to a
>>>>> CoCo cart so you could take advantage of the Boisy Interface/Becker
>>>>> port so that you could have faster access to drivewire 4 server?
>>>>>
>>>>
>>>> What is the Boisy Interface/Becker port?
>>>>
>>>
>>> This is a fifo buffer interface implemented initially in the CoCo3FPGA
>>> project and since ported to some emulators.  It allows DW to operate
>>> at very high speed/low cpu use compared to bitbanger on those
>>> platforms.  OS9 modules to support the interface are in the NitrOS9
>>> source.
>>>
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