[rescue] Anyone got a spare CalComp stylus?

[Richard]

In article <20060320151614.GA6337 at jdboyd.zill.net>,
    Joshua Boyd <jdboyd at jdboyd.net>  writes:

> On Sun, Mar 19, 2006 at 01:50:52PM -0500, Phil Stracchino wrote:
> > Anyone have a CalComp digitizer-pad stylus and/or puck lying around?  I
> > have a CalComp Creation Station II 12x12 pad, for which we appear to
> > have mislaid the stylus, and they're no longer available (CalComp having
> > long since been bought out by GTCO).
> 
> I can't help you.
> 
> However, I was wondering if anyone understood how these tablets worked
> and could be bothered to explain it.

I have a Summagraphics tablet that I got recently from ebay.  It came
with 3 controller boxes, several pucks and styluses (stylii?).  The
controller box has an 8080A, some EPROM and some MSI/SSI TTL logic in
it.  The controller looks fairly simple, I'm willing to bet that most
of the logic is in the 8080A program.  There is a piece of paper
attached to the tablet that talks about magnetizing it properly.  The
tablet has two 9-pin old PC style keyboard type connectors attached to
two leads.  The tablet controller has 3 LEDs labelled "X-axis",
"Y-axis" and "Power".  I don't have any instructions on it, but I'm
guessing that the tablet uses some sort of field gradient across the
tablet and induces a field response in a wire loop in the puck/stylus.
The remaining signals on the puck/stylus lead are for the switches on
the puck/stylus.
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