Main Control Board (Board-Com) - OKIDATA Okipage 16n Service Manual

2.1 Main Control Board (BOARD-COM)

The control board consists of an one chip CPU, LSIs, program/font ROM's, DRAM's, 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, 32-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
DRAM controller
Parallel interface controller
Timer
Serial I/O port
I/O port
Option I/O interface
(2) Program/font ROM's
The program/font ROM's store the HP IV emulation program and various types of font. MASK ROM is
used as the program/font ROM's.
(3) DRAM's
2-Megabyte DRAM (4 Mbit DRAM x 4) is mounted as resident memory to be used for storing
the program and providing various buffers. This DRAM is expandable up to 66 Mbytes by
adding expansion memory (SIMMs). This DRAM provides the areas shown in the following
table.
Memory area Use
System area Working area used for the program Fixed
Raster buffer Stores converted bit image data
Receive buffer Stores temporarily the data
received from the host interface
Page buffer Adds print information to the
analyzed receive data and stores
the resulted data.
DLL/macro buffer Stores soft fonts and macro data.
Service Guide OKIPAGE16n
Chapter 2 Operation Description
Control of ROM, DRAM and I/O device
Transfer of image data from DRAM to OST LSI
Control of Centronics parallel interface
Generation of various control timing
Monitoring of paper running and paper size
Control of operator panel, EEPROM, and options
Inputting/outputting of sensor, signal and motor signal
Control of OKI HSP interface
MENU
Enable
Enable
-
-
Function
Memory capacity setting
Expansion RAM
Fixed
Expandable
Expandable
Expandable
Expandable
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