This PCB board is optionally available. Using this board allows the system to be ready for additional G3 line. This board is connected to the MCNT board through

the OKI's original MUPIS interface.

And this board is connected to the NCU board through the DM2 board.

The block diagram of this board is shown on the next page.

This board is connected to the MCNT board with an 80-pin connector (CN1). One pin of this connector (RM2) is signal line dedicated to the G3A board, and

fourteen pins of this connector are signal lines shared with the option G4A board, and the remaining 64 pins are signal lines shared with the optional G4A board

and LAN network board. It is connected to the NCU board through the DM2 board with 30-pin connector (CN2).

Data is transferred to/from the CPU on the MCNT board via the 2KB dual port RAM. When data is sent, the MCNT board causes an interrupt to the G3A board

using a CUREQ-N signal and writes data into the 2KB dual port RAM.

The G3A board reads the data from the dual port RAM in the DRAM, and sends the data to the NCU board via the DM2 board.

When data is received, the G3A board causes an interrupt to the MCNT board using an OPREQ signal and writes data from DRAM into the dual port RAM. The

MCNT board reads data from the dual port RAM, expands the data in the DRAM on the MCNT board, and sends the data to the LED head via the IOGA5.

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