Page: 15Service Guide PM3410Chapter 2 Principles of Operation2.1.02 Microprocessor (MPU) and Peripheral CircuitsMicroprocessorQ3: M67X640V1The MicroProcessor Unit (MPU) is the nucleus of the control circuit. Various peripheral circuits operateunder program control of this microprocessor. The MPU (Q3) controls all aspects of printer operation.Program ROM for the MPUQ4: 27C202KThis 2Mbit Read Only Memory (ROM) contains the control program for the printer. The MPU operatesunder program control.This ROM also stores the resident character fonts.DRAMQ10 and Q11The Dynamic Random Access Memory (RAM) chips, each consisting of 64 K x 4 bits, are used as theCommand Buffer, Receive Buffer and Print Buffer.The total buffer size is 64 K x 8 bits. The RAM speed is 120 ns.EEPROMQ14: 93C06NThis 256-bit serial Electrically Erasable and Programmable Read Only Memory (EEPROM) stores themenu data and initial settings for the LSI circuits.Interface/Motor Control LSIQ5: B562 13497This LSI controls the following functions listed below.Space Motor Enable / Speed ControlTo obtain the carriage speed instructed by the microprocessor, Q5 uses the signals SP - Phase A and SP- Phase B, derived from space motor movement to generate the pulse width timing and overdrive time.Line Feed Motor Phasing ControlTo turn the line feed motor in the proper direction, this LSI sends motor drive signals (properly phased) tothe line feed driver (TRA4).Bail Motor Phasing ControlTo turn the bail motor in the proper direction, this LSI sends motor drive signals (properly phased) to thebail driver (TRA3).Dot ON Timing signal generationQ5 uses the signals SP - Phase A and SP - Phase B, derived from space motor movement, to producethe signal IPT. This signal (IPT) is used to enable the print wires at the desired carriage position.Printhead / Bottom Tractor Feed Control LSI
