OKIDATA ML380, Руководство по обслуживанию

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Service Guide ML380
Chapter 2 Principles of Operation
2.1.02 Microprocessor and Peripheral Circuits
Microprocessor (Q5: 83C154GS-551-V1K)
The microprocessor is the nucleus of the control circuit. Its peripheral circuits operate under program
control by this microprocessor. The I/O ports of the microprocessor are connected to the address bus,
data bus, and control lines.
Program ROM (Q2)
The program ROM (256 Kbit) contains the control program for the printer. The microprocessor operates
by execution of this program.
RAM (Q4)
The RAM stores received data (to be printed). (32 Kbytes)
CGROM (Q3)
1 MBit ROM which stores the resident character fonts.
EEPROM (Q18)
This 256-bit serial Electrically Erasable and Programmable ROM stores the Menu Mode data.
LSI (Q7: LC92018B-283)
This LSI switches the phase of the space motor, and generates the timing of print dots for each print
density. The LSI performs the following functions.
Space Pulse Motor Control
To obtain the carriage speed instructed by the microprocessor, the LSI generates the pulse switch timing
and overdrive time.
Dot Timing generation
Parallel Interface Control
LF Motor Control
LED Drive
General Purpose Input Port
Used to read Operator Board Switches.
LSI (Q6: LC92011B-284)
This LSI drives the 24 pin printhead and controls memory. The following describes the function of the LSI.
Printhead Drive Control
Head Pin Counting Function
Counts the number of printwires to be driven then, changes the duration of the HD ON signal accordingly.
Memory Control
Extends the addressable memory by switching banks in/out.
LED Drive Output Port
Microline 380 Block Diagram