Oki OL1200, Service Manual, Page: 19 / 272

Page: 9
Service Guide OL1200
Chapter 2 Operation Description
2.1 Main Control Board (AOLM-PCB)
The control board consists of a one chip CPU, LSIs, a program/font ROM, a DRAM, an EEPROM, a 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, 33-MHz clock) that
incorporates a RISC CPU and its peripheral devices, and has the following functions:
Built-in device Function
Chip select controller
Bus controller DRAM controller Control of ROM, DRAM and I/O device
DMA controller Transfer of image data from DRAM to OST
LSI
Parallel interface controller Control of Centronics parallel interface
Serial interface controller Control of RS-232C serial interface
Timer Generation of various control timing
Monitoring of paper running and paper size
Serial I/O port Control of operator panel, EEPROM, and
options
I/O port Inputting/outputting of sensor, signal and
motor signal
Option I/O interface Control of OKI HSP interface
(2) Program/font ROM
The program/font ROM stores the equipment program and various types of fonts. EPROM/ OTP or
masked ROM is used as a program/font ROM.
(3) Memory
2-Megabyte DRAM (512K x 4) is mounted as resident memory to be used for storing the program and
providing various buffers. This DRAM is expandable up to 34 Mbytes by adding expansion memory
(SIMMs). This DRAM provides the areas shown in the following table.
Memory capacity setting
Memory area Use MENU Expansion RAM