Multiplayer extension board used with Kizuna Encounter - Super Tag Battle to allow 4 players to play on the same system. It forms a Y splitter with 2 JAMMA edges to connect two displays, two pair of speakers and two sets of 2-player controls.
It multiplexes the inputs by using selection signals coming from a 4-wire (actually 2 used) cable that connects to the output port of the MV1B or MV1C, it also provides video signal buffering and power for the speakers (power amp under the heatsink).
The REG_POUTPUT register is used to detect the board and select which set of inputs to read.
- OUT1: set selection
- OUT2: seems unused
- OUT3: used for board detection by the system ROM
|OUT1||P1 reads||P2 reads|
|low||EDGE 1 P1||EDGE 2 P1|
|high||EDGE 1 P2||EDGE 2 P2|
When OUT3 is high, it simulates presses on particular buttons:
- EDGE 1 player 1 button A
- EDGE 2 player 1 button A
- EDGE 1 player 2 button B
- EDGE 2 player 2 button B