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Part 4: Technical Reference
BJC-2000
4.2.2 Logic section components
1) MPU & Printer controller (IC3)
The MPU & Printer controller contains a 16-bit CPU, 1K-bit RAM, 21-bit address bus
port, 16-bit data bus port, stepping motor controller, interrupter controller, A-D
converter, interface controller, print head controller, buffer controller, DRAM
controller, EEPROM controller, I/O ports, and other components.
Built-in CPU
The 16-bit CPU operates in synchronization with a 20 MHz external clock input.
Address bus
The 21-bit address bus port is connected to an 8 M-bit control ROM. The controller
synchronizes with the read signals output by the MPU and Printer controller.
Data bus
Like the address bus, the 16-bit data bus port is connected to the 8 M-bit control
ROM.
Stepping motor controller
The stepping motor controller outputs the carriage motor single- and two-phase
exciter drive signals and paper feed motor two-phase drive signals.
The stepping motor controller switches the carriage motor with the 5-step peak
current value for optimum drive. The stepping motor controller outputs the
switching control signal to the carriage motor driver.
A-D converter
The following analog signals are detected after they pass through the built-in A-D
converter:
AN0: The printer's internal temperature is detected by the thermistor on the logic
board.
AN1: The head temperature is detected by the head temperature sensor in the BJ
cartridge.
AN3: The head rank is detected by the rank resistor in the BJ cartridge.
Interface controller
The interface controller receives, from the computer, 8-bit parallel data which is
synchronized with the data strobe pulse (STROBE) through the BUSY/ACKNLG
handshake. It also controls other interface signals.
The data received through the interface is stored in the DRAM's receive buffer and
analyzed by the MPU.
When the printer initialization signal INIT is input through the interface to the
printer controller, the printer controller outputs a BUSY signal. Also, after INT1 is
output to the MPU and print data in the print buffer is printed, the printer is
initialized.
DRAM controller
The DRAM controller controls the 10-bit address/16 bit data bus of the 4 M bit
DRAM, and also performs the read/write control, and refresh control.
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