[Coco] coco x10 interface programming (conjecture)

[John W. Linville]

This has been an on-again/off-again interest for me in the past, but
mostly just preliminary research.  Hence, I have no code to back-up
anything I speculate below. :-)

It seems clear that two cassette-port based X10 (i.e. "plug 'n power")
interfaces were sold.  The earlier one (26-1182) was really intended
for the Model I/III/IV, but apparently included a CoCo program on
the included cassette tape.  The later one (26-3124) included a CoCo
Program Pak, but it used a graphics mode that makes it incompatible
with the CoCo3.

The earlier model is relatively simple hardware, but making use of
it requires a reasonably complete understanding of the X-10 "wire"
protocol.  The programming of this device is conceptually similar to
the more modern PL-513 or TW-523 devices.  The details are covered in
a series of articles in Rainbow magazine, particularly "X10 Protocol
Theory Home Power Control Part 3" in the June 1983 issue of Rainbow.

The later model's hardware is a bit more complex.  This makes
sense, since it contains extended functionality such as the
ability (once programmed) to issue X10 commands without an
attached computer.  The hardware includes an 8048 microcontroller
and a 6116 RAM.  The hardware seems to be similar to the
contemporary CP290 interface available for other computers.
(See "corrections on X-10 remote controller/RS coco." in
http://www.retroarchive.org/cpm/cdrom/SIMTEL/ARCHIVES/CPM/8804-1.TXT
for more information.)  I suspect that the 26-3124 device and the CP290
devices are essentially two versions of the same hardware platform.
(See http://www.eddriscoll.com/timeline.html for the basis of my
suggestion.)

I have seen it stated more than once that the 26-3124 device is
accessed with the same sort of FSK signalling as is used for reading
and writing casette data.  So, here is my (completely untested)
hypothesis: the 26-3124 device is programmed using the same physical
data signalling as is used for the cassette data, but using the same
logical signalling as is used for the later/contemporary CP290 device.
The functional similarity between this device and the CP290 makes
this seem at least plausible.

I am uncertain (mostly due to laziness) as to whether or not the
CP290 is programmed similarly to the more modern CM11A.  FWIW,
I found at least one program that supported the latter but not the
former -- YMMV.  Fortunately, the programming information for the
CP290 is still available for download:

	http://www.smarthome.com/manuals/MAN-1130_31p.pdf

Someday I hope to see my hypothesis tested.  But, I have a long list
of projects ahead of that. :-(	Anyone should feel free to test it
out for themselves -- please let me know how it pans-out! :-)

Sorry for the long post -- my hope is to at least have this
research/hypothesis documented for posterity (or my own future
renewed interest)...

Thanks,

John
-- 
John W. Linville                Someday the world will need a hero, and you
linville at tuxdriver.com                  might be all we have.  Be ready.