[Coco] RaspberryPI DriveWire server

[Gene Heskett]

On Sunday 28 October 2012 16:15:42 David Ladd did opine:

> Right now I am working on a way to recreate the Boisy Interface/Becker
> port as a real card to interface with the GPIO on the Raspberry Pi.
> Though the two USA distribution locations I tried to order from are
> back ordered a month so as soon as I get my Pi and my FIFO chips I
> will start on it.
> 
> Plus using the GPIO as a full 8 bit parallel mode should increase speed
> as well.
> 
> For my test platform I am going to use my J&M CP FDC since the
> parallel port on it uses the same FF44 port for in and out.
> 
Be aware that the CP, while nice on the slower .779 clocked cocos, turns 
into a /dev/null for about 20% of what is sent to it.  The FCC mandated 
noise filtering in the printers with a parport, such as the later DMP's and 
CG's slows down the strobe pulse, which is the same width as the chip 
access, to the point that by the time the printer see's a strobe, most of 
the data is already gone as the port tristates at the end of the pulse.

So the CP really needs a buffer that includes a busy signal when its been 
written but not yet read, going both ways.  A one byte buffer each way 
would do as long as the busy bits are honored going both ways.

> One of the problems will be getting the HDBDOS DW updated so there is
> a becker version of the drivers.
> 
> As far as NitrOS-9 goes it already has a becker driver created and
> tested working with CoCo3FPGA, Patched MESS, and modified VCC.

The current pull from the Mercurial repo is not even building it, I believe 
because it is building becker_* stuffs, but then looking for ccbkrn when 
trying to build the dsk's boottrack.  Fails of course. :( 

> I will update what I have going on once I have more info to share.
Please do.

Cheers, Gene
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