Canon multipass c3000 Service Manual (en)

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a-4) Main ROM (IC301)
This 8 Mbit ROM contains the control programs (e.g. operation panel, scanner and
communications section etc.) for this fax.
a-5) SRAM (IC 302) 
This 256 Kbit SRAM is backed up by lithium battery.  SRAM holds data registered for
system control and communications management information.  Also, SRAM stores
shading correction data.
a-6) DRAM (IC 303, IC 307) 
Two 4 Mbit DRAMs are used as memory for storing image data, and as an MPU work
area.
b) Communication control section
b-1) Modem IC (IC 701)
A Rockwell R144EFXL PQFP is used as the modem IC. The MODEM IC carries out G3
modulation conforming to ITU-T standards V.27ter, V.29, V.17 and V.33 on transmitted
data received from the MPU during transmission.  During reception, the MODEM IC
carries out G3 modulation on received signals from the telephone line, according to the
same standards.
c) Document scanning section
c-1) System controller IC (IC 401)
The system controller IC include image processing function (UHQ-6.5) are as follows:
• A/D conversion
Input signals from the contact sensor are A/D converted.
• Generation of shading data
• ABC (Auto Background Control)
Sets the slice level for each scan line.
• Edge enhancement processing
• Binaryzation processing
• Halftone processing
c-2) SRAM (IC 402)
This 256 Kbit SRAM is used as a buffer for the image processing data and shading
correction data.
Chapter 2: Technical Reference
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