Operation Manual

3-68
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.