Canon MultiPASS C5000 Service Manual page 203

Part Printer
a) MPU (ICI)
Printer controller (IC5) is controlled by the ControVCG ROM (IC3) program to control
printer mode operations.
b) ControllCG ROM (IC3)
Besides the printer hardware control program and font image data, the following data are
stored in the Control/CC ROM.
Emulation software
l
This is the control program for the printer, which can emulate either IBM Proprinter
Font image data
l
When the printer is emulating IBM Proprinter X24E, the character designs from
Character Set 1, 2, All Characters Chart, Code Page; 437(USA)/ 850 (Multilingual)/ 852
(East Europe)/ 855 (Cyrillic)/ 857 (Turkish)/ 860 (Portuguese)/ 863 (Canadian French)/
864 (Arabic)/ 865 (Norway)/ 869 (Greek) can be selected. When the printer is emulating
EPSON LQ-2550, the EPSON Italics Character Set, EPSON Graphics Set can be
selected, and the language chosen from the International Character Set.
Mask patterns in fine mode
l
c) Printer controller (IC5)
The main functions of the system controller as follows:
Interface controller
l
The centronics interface controller receives 8.bit parallel data sent from the computer in
synchronization with the data strobe pulse by BUSY / -ACK handshaking It controls
other interface signals. The data received from the interface are stored in the receive
buffer in DRAM, and is analyzed by the MPU. If the printer initialize signal -1NIT is
input to the printer controller and MPU f ram the interface, the printer controller
outputs the BUSY status immediately, and the MPU prints printing data stored in the
print buffer, then initializes th? printer.
Buffer controller
l
The buffer controller automatically writes received data into the receive buffer in
DRAM, controls the remaining data in the receive buffer, reads data from the receive
buffer, and clears data after rending.
d) DRAM (IC4)
Besides the printer hardware contrul data storage area, the DRAM comprises the
following;
. Input buffer
Reception data from the intrrf,rcr are stored momentarily. The data are then analyzed
by the MPU, and then erased to make ro"m for the next data.
Printer buffer
l
Two lines of BJ cartridge print data are stored. After being printed out, the data are
then erased to make room for tbc next data.
Download buffer
l
When emulating the IBM Proprinter X24E, besides the data stored in the ROM, font
2-6