In message <m0ruGcw-000DCnC@dopey.me.iastate.edu>, you write:
>This may be PIC related...
>
>I went to the MegaZone in Morecambe last night, it is a laser gun game
>arena, like QZar and Laser Quest.  Normally you are known as 'Player 1'
>etc., but if you purchase club membership you get your own name stored on
>the computer to identify you.  To activate this feature you are given a tag
>which looks exactly like a button cell (or lithium battery).  You press the
>cell against two contacts (centre and edge, like + and - contacts for a
>power cell) and somehow the cell returns a unique code.  One of the cells
>was manufactured by Dallas.  How do they work?
>

The Dallas part is probably one of their "Silicon Serial Numbers" (basically a
serial ROM), which uses Dallas' one-wire bus. This is a novel bus which uses a
single wire for power, clock and data. Interesting devices, these. While we're
on the subject, does anyone have PIC code for talking to this bus? The
protocol looks to be a bit on the complicated side. :-)

                                                        --Monty

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