Main Control Board - Oki OKIPAGE 14EX Service Manual

Service Manual for OKIPAGE 14ex

2.1 Main Control Board

The main control board consists of a single chip CPU, two program/font ROMs, four DRAMs, an EEPROM, a host interface circuit, and a mechanism driving
circuit.
(1) Single chip CPU
The single chip CPU is a custom CPU (32-bit internal bus, 32-bit external bus, 32-bit external bus, 49.766-MHz clock, which incorporates the RISC CPU and its
peripheral devices, and has the following functions:
Built-in Device
Chip select controller
Bus controller
DRAM controller
DMA controller
Parallel interface controller
Serial interface controller
Video output port
LED STB output port
Timer
I/O Port
(2) Program and Font ROMs
The Program and Font ROMs store the equipment program and various types of fonts. Mask ROM is used as Program and Font ROMs. The mounting locations
of these Program and Font ROMs vary depending on the type of the ROMs.
(3) DRAM
The DRAM is a 2MB resident memory on the main control board that stores edited data, image data, DLL data and macro data.
(4) EEPROM
4,096-bit Electrically Erasable PROM (EEPROM), is loaded with the following kinds of data:
Chapter 2 Operation
Function
Control of ROM, DRAM and I/O device.
Transfer of image data from DRAM to video output
port.
Control of Centronics parallel interface.
Control of RS-232C serial interface.
Controls LED head.
Generation of various control timing
Monitoring of paper running and paper size.
Input and output of sensor and motor signals.
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