Canon FAX-L1000 - Manual (Page 212)

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FAX-L1000 Chapter 3: Technical Reference
a) System control section (SCNT board)
The system control section consists of the following components and controls the entire
facsimile system.
a-1) MPU (Micro Processor Unit) (IC 17)
The MPU, on NEC UPD70741GC-25-7EA, has the following main functions.
•16-bit CPU
•24-bit address bus
•16-bit data bus
•Software CODEC
•Interrupt control unit
• The CPU controls interrupts from the system controller IC, and the others the inside.
•CSI (Clocked Serial Interface)
a-2) System controller (IC 18)
The system controller is a gate array for controlling MPU peripheral devices.
The main functions of the system controller are as follows:
•DMA controller
•DMA interface
•DRAM controller
•ESS control
•Chip select
•NMI generator
• Generate NMI for ESS mode cancellation (cancellation in CPU stop mode)
•CI pulse width counter
•Timer
• Used to generate dial pulses
•Clock divider
• Generate basic clocks (16 MHz) for codec IC (IC22)
•CPU interface
•CODEC interface
•UHQ-6.6 interface
•Row to column converter
• Specify the DRAM address
•R.T.P.
• Fine adjust the motor speed during high speed scanning in Ultra Fine or Super Fine mode
•16-bit serial interface
• Serial interface to gate array on the operation panel
a-3) EP-ROM (IC 4)
The 8-Mbit EP-ROM contains the control program for the operation section, read section,
and communication control section of the fax.