Main Control Board (Board-Fff) - Oki OKIPAGE 24DX Service Manual

2.1 Main Control Board (BOARD-FFF)

The main control board consists of a one-chip CPU, LSI, program/font ROM's, DRAM's, EEPROM, host
interface circuit, and a mechanism driving circuit.
(1) One-chip CPU
The one-chip CPU is a custom CPU (32-bit internal bus, 32-bit external bus, 120-MHz clock) that
incorporates an RISC CPU and its peripheral devices, and has the following functions.
Built-in Device
Chip select controller
Bus controller
DRAM controller
DMA controller
Serial interface controller
Parallel interface controller
Timer
Serial I/O port
I/O port
Motor driver controller
Image processing circuit
(2) Program/font ROM's
l
PCL ROM
The program/font ROM's store the HP LJ5 emulation program and various types of font. MASK ROM
is used as the program/font ROM's.
l PS ROM
The program/font ROM's store the Adobe PostScript Level 2 program and its fonts.
(3) DRAM
16-Megabyte DRAM (64 Mbit DRAM x 2) is mounted as resident memory to be used for storing the
program and providing various buffers. This DRAM is expandable up to 128 Mbytes by
adding expansion memory (SIMMs). This DRAM provides the areas shown in the following table.
Service Guide OKIPAGE 24DX/24DXn
Chapter 2 Operation Description
Function
Control peripheral LSI, ROM, DRAM and I/O device.
Transfer of data Host I/F to RAM
Control of RS232C serial interface.
Control of Centronics parallel interface.
Generates various control timings for monitoring paper
feeding and a paper size.
Inputting of various signals
Outputting of various control signals
Inputs and outputs the sensor signals and motor signals, etc.
Also performs I/O for EEPROM.
Control of Main Motor.
Executes the image data process for printing.
Page: 11