Main Control Board - Oki OKIPAGE 8z Service Handbook

2.1

Main Control Board

The main control board consists of a one-chip CPU, a program ROM, a DRAM, an EEPROM, a
host interface circuit, and a mechanism driving circuit. The mechanism driving circuit consists of
a LED head, a main motor, and an electromagnetic clutch.
(1) One-chip CPU
• OKIPAGE 8z
The one-chip CPU is a custom CPU (8-bit internal bus, 8-bit external bus, 16-MHz clock)
incorporating mask ROM and CPU peripheral devices. This CPU has the functions listed in
the table below.
Built-in Device
DRAM controller
DMA controller
Parallel interface controller
Video output port
LED STB output port
Timer
I/O port
A/D converter
Controls DRAM.
Transfers image data from Parallel I/F to DRAM, from DRAM to a video output port and
between CPU and DRAM.
Controls the parallel interface.
Controls LED head.
Generates various control timings for monitoring paper feeding and a paper size.
Inputs and outputs the sensor signals and motor signals, etc.
Also performs I/O for EEPROM.
Inputs the feedback signals from a high-voltage generation circuit and thermistor signal.
2 - 3
Function