G4N-Pcb - Oki OKIFAX4550 Maintenance Manual

9.

G4N-PCB

This PCB board is optionally available. Using this board allows the system to be ready for the G4
protocol.
The block diagram of this board is shown on the next page.
This board is connected to the MCNT board with a 50-pin connector (CN1). 23 pins of this connector
are signals lines dedicated to the G4N board, and the remaining 27 pins are signal lines shared with
the NCU board.
Data is transferred to/from the CPU on the MCNT board via the 2-KB dual port RAM. When data is
sent, the MCNT board causes an interrupt to the G4N board using a CUREQ-N signal and writes data
into the 2-KB dual port RAM. The G4N board expands the data from the dual port RAM in the DRAM,
and sends the expanded data to the line via the driver.
When data is received, the G4N board causes an interrupt to the MCNT board using an OPREQ-N
signal and writes data from the DRAM into the dual port RAM. The NCNT 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 IOGA4/IOGA6.
41309401TH Rev.4
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