Microprocessor (Mpu) And Peripheral Circuits; Microprocessor; Program Rom For The Mpu; Dram - OKIDATA Pacemark 3410 Service Handbook

2.1.02

Microprocessor (MPU) and Peripheral Circuits

Microprocessor

Q3: M67X640V1
The MicroProcessor Unit (MPU) is the nucleus of the control circuit. Various peripheral
circuits operate under program control of this microprocessor. The MPU (Q3) controls all
aspects of printer operation.

Program ROM for the MPU

Q4: 27C202K
This 2Mbit Read Only Memory (ROM) contains the control program for the printer. The
MPU operates under program control.
This ROM also stores the resident character fonts.

DRAM

Q10 and Q11
The Dynamic Random Access Memory (RAM) chips, each consisting of 64 K x 4 bits, are
used as the Command Buffer, Receive Buffer and Print Buffer.
The total buffer size is 64 K x 8 bits. The RAM speed is 120 ns.

EEPROM

Q14: 93C06N
This 256-bit serial Electrically Erasable and Programmable Read Only Memory (EEPROM)
stores the menu data and initial settings for the LSI circuits.
Principles of Operation 2 - 2 Pacemark 3410