Canon fax basic 2000 서비스 매뉴얼

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FACSIMILE SYSTEM

2. SCNT BOARD

“SCNT board” is an abbreviation of System CoNTroller board, and per-

forms control of the entire facsimile system. The control functions of the

SCNT board can be broadly classified into the following four control sec-

tions:

• System control section

• Communications control section

• Reading control section

• Printer control section

Fig. 6-2   System Block Diagram

2.1

System Control Section

This section comprises an 

, system controller, memory (SRAM and

DRAM), main ROM, real-time clock (

) and other components. A cod-

) is sometimes used on some facsimile mod-

els. Each of the ICs in the system control section is connected by a 

excluding the RTC.

The MPU has a built-in 

 controller for increasing the efficiency of

. The DMA controller performs DMA transfer between each of

the ICs that require transfer of large amounts of data, for example, between

MPU

MODEM

b)

SRAM

MPU

ROM RAM

DRAM

SRAM

RTC

c)

d)

a)

a) System control section
b) Communications control section
c) Reading control section
d) Printer control section

OPCNT board

System controller

Main ROM

Address bus

Data bus

NCU board

Telephone line

Image

processor

IC

Contact sensor

Printer

controller

Printer

SCNT board