Canon multipass c3000 Service Manual (en)

a) MPU (IC1)
Printer controller (IC5) is controlled by the Control/CG ROM (IC3) program to control
printer mode operations.
b) Control/CG ROM (IC3)
Besides the printer hardware control program and font image data, the following data are
stored in the Control/CG ROM.
• Emulation software
This is the control program for the printer, which can emulate either IBM Proprinter
X24E, or EPSON LQ-2550.
• Font image data
The 360 dpi character design data for each of the BJ cartridge nozzles.
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
c) Printer controller (IC5)
The main functions of the system controller as follows:
• Interface controller
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 -INIT is
input to the printer controller and MPU from the interface, the printer controller
outputs the BUSY status immediately, and the MPU prints printing data stored in the
print buffer, then initializes the printer.
• Buffer controller
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 reading.
d) DRAM (IC4)
Besides the printer hardware control data storage area, the DRAM comprises the
• Input buffer
Reception data from the interface are stored momentarily.  The data are then analyzed
by the MPU, and then erased to make room for the next data.
• Printer buffer
Two lines of BJ cartridge print data are stored.  After being printed out, the data are
then erased to make room for the next data.
• Download buffer
When emulating the IBM Proprinter X24E, besides the data stored in the ROM, font
image data are transferred from the computer and stored.
Part 2: Printer