[Coco] CoCo and Rasberry Pi ( and Software Rant )

[Frank Pittel]

I here a lot about "plugging" a pi into a coco and always wonder if the coco
power supply has enough power drive it. The specs I've seen shows that the model
A uses 300ma and the model B uses 700ma. That seems like a lot of power for the
undersized PS in the coco!! One possible solution would be to "dump" the internal
supply and use a wall wart type supply to power the pi and coco. I've got a couple of
usb supplies that put out 5V at 2.1 amps and I've seen some that put out 3A.

The Other Frank





On Wed, Apr 10, 2013 at 10:01:26AM -0400, Brett Gordon wrote:
> I propose this:
> 
> A Rasberry Pi running DW interfaced into the coco via an interrupt
> driven 8 bit becker/boisy port, with some Flash ROM similar to
> SuperIDE.
> 
> Why a Pi ?   Your coco could use anything that Linux supports via USB:
> keyboard, mouse, joystick, harddrives, smartcard readers, MMC/SD Flash
> readers, Serial Ports.  Oh yeah: I guess the Pi's HDMI and Composite
> Video is there too.  Let's use the Pi for some cool graphics!  ( I
> believe DW4 has some basic support for this, BTW).  Oh yeah the PI is
> amazingly cheap.
> 
> The Flash ROM solves a very basic software problem we have: it's plain
> crappy to boot the CoCo:    it's entirely static.  ROM: that's all you
> have.  Even after you boot from ROM you get a static enviroment:  both
> RS-DOS and RBF systems have NO SUPPORT FOR PARTITIONING.  This is
> stupid. Disk Partition Tables have been agreed upon and in use in the
> MAC/PC world since the late 1970's.  It is unacceptable and poor
> programming practice that our two main OS's don't support partition
> tables.  The most hideous part of writing the HDB/IDE drivers for the
> original CoCoBoot was the fact that I had to rely on the USER knowing
> or grokking around in ROM to manully tell me where a HDB partition
> might sit (AKA the HDB-OFFSET ).  This is plain wrong. ** We now have
> open-source HDB-DOS, and a open-source Nitros9.   It's time to drop
> the legacy of crappy software design.
> 
> Why an interrupted 8 bit becker/boisy port?  8 bits is our inherent
> data bus on the 6809.  16 bits would be a touch faster on the 6809,
> but 8 bits is more doable on the Pi than 16 bits.  Yes, DMA would be
> awesomely faster, but has two drawbacks: (1) unless the DMA controller
> could put drive data exactly where our OS's want it, then its no
> faster than a plain becker/boisy port. and (2) this is complicated.
> ***
> Modern OS design calls for a Hardware Interrupt, NOT polling.
> 
> 
> -- 
> Brett M. Gordon,
> beretta42 at gmail.com
> 
> 
> ** Beretta's Rules of Programming No. 2. Computers count well, people don't.
> *** Beretta's Rules of Programming No. 9: Simplicity Good!  And rule
> No. 10: Complexity Bad!
> 
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