Oki OKIFAX4550 Maintenance Manual page 296

(12) G4 TX mode
Figure A.5 (12/13) shows the signal route of this mode.
The signal route from the image sensor to the LC821033, DRAM, IOGA6, CPU, and DRAM is
the same as that of the item (2), "G3 send mode".
The read one-line image data is stored in the DRAM, encoded by the CPU and again stored in
the DRAM.
In G4 TX mode the encoded data is transferred by the control of CPU to the dual-port
RAM(DPRAM) on the G4N board. The transferred data is sent to a line via the ISDN controller
and ISDN driver by the control of the CPU on the G4N board.
(13) G4 RX mode
Figure A.5 (13/13) shows the signal route of this mode.
The signal received from an ISDN line is transferred to the dual-port RAM (DPRAM) by the control
of the CPU via the ISDN driver and ISDN controller of the G4N board.
Notified of the existence of received G4 data by interruption, the CPU of the R46 board transfers
the data from the DPRAM to the DRAM.
The signal route from the DRAM to the LED head is the same as that of item (3) "G3 receive
mode".
The CPU reads out the data stored in the DRAM and decodes it to store it again in the DRAM.
The data is transferred to the IOGA6 (printer control) by the DMA, converted into image data, and
transferred to the LED head for printing.
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