The technical spec of the Go Between are relatively straightforward, although the reality of implementing it is something entirely more frustrating and thankless.

Tech overview
A Pic microcontroller handles all the sensing and display on each board. The networking on each board is handled by the Cobox Micro, which receives serial data from the Pic and translates it into a TCP stream sent to a Java chat server. The Java chat server relays that message to the other board (and any observers).

Sensors
The sensing of moves relies on Hall Effect sensors embedded underneath the surface of the board. Each stone contains a small magnet that activates the Hall sensor when placed on the board. Each activated sensor feeds into a parallel-in, serial-out 8-bit shift register. Due to the nature of the game, only one sensor will be activated per move.

Display
The display of the opponent’s moves results from an inductive coil also embedded underneath the surface of the board at each intersection. Also in each stone is a coil and LED in series that makes the stone light up when placed above the activated inductive coil in the board. Power to the inductive coils is fed in a row-column csanning matrix. A series of 3 to 8 demultiplexers send power to one row at a time. Serial-in to parallel-out 8-bit shift registers control which coils in a given row are active.