Canon multipass c3000 Service Manual (en)

6.2 Circuit Board Components
a) System control section
The system controller is made up of the following components, and controls the entire fax
a-1) MPU (Micro Processor Unit) (IC 201)
The main functions of the NEC µPD70433GJ-16-3EB MPU are as follows.
• 16 bit CPU
• 24 bit address bus
• 8 bit data bus
• DMA control
• A/D converter
• Serial interface
• Software CODEC
• Interrupt control unit
a-2) System controller (IC 401)
The system controller is a gate array for controlling MPU peripheral devices.  The main
functions of the system controller are as follows:
• Printer resolution conversion (Ultra-smoothing)
This IC converts facsimile data of horizontal resolution of 8 dots/mm and vertical
resolution of 3.85 or 7.7 lines/mm to print data of 360 dpi and 360 dpi, respectively.
• BJ printer interface 
8 bit parallel print data sent to the Printer controller.
• OPCNT serial interface (Contains document sensor and document edge sensor signals)
• DRAM/SRAM controller
Controls DRAM/SRAM read/write and renewal.
• Document feed motor control
• Serial-to-parallel conversion
• Horizontal scaling
• Detection of document edge sensor and ink detection sensor
a-3) RTC (Real Time Clock) IC (IC 203)
RTC4543 is used as the RTC.  The RTC IC is backed up by lithium battery, and counts
the date and time.
Part 1: Facsimile