Thanks again.
There are still some doubts. I'll be very grateful if you can help me again.

Do you have some literature, or site in the net, about the working principle of these boards?

AN0 to AN5 stands for Memory Address Number? or something Analog ?

I don't know the purpose of the Sense pin also.

Xrst may be external reset, Dgnd Digital ground and Vcc voltage supply.

DACA to DACC may be digital to anolog converter A,B and C. But why 3 of them?
Is the amplifier and audio circuits in A70 or inside the board?

Is Sdata and Sclk a secondary serial port?
What kind of data is transmited on it?

Is Clk,Rxd and Txd another serial port? Is it used to receive MIDI info or a proprietary Roland protocol?

Regards,
Fernando