KV-S7075C (serv.man2) - Panasonic Other Service Manuals Service Manual (repair manual). Page 127

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This scanner has 2 CISs (CIS (F), CIS (B)) to scan image signals for front and back sides respectively, in order to perform
duplex scanning. 
Both of them are available for duplex scanning in ADF mode. (When scanning on the Flatbed, only a CIS (F) is available.)

ASIC (F) (IC1011) requires SDRAMs (IC1015 to IC1018) to memorize and output pre-processed or post-processed
image data for the front side. 
And an additional memory (SO-DIMM) can be installed in CN1005 for image data-output.

ASIC (B) (IC1013) requires SDRAMs (IC1019 to IC1020) to memorize and output pre-processed or post-processed
image data for the back side. 
And an additional memory (SO-DIMM) can be installed in CN1006 for image data-output.

When a scanning starts, via CIS (F) RELAY Board, analog pixel signals scanned by CIS (F) are transmitted to 
AFEs (IC2009 to IC2012) on the CENTER Board.
At the same time, via CIS (B) RELAY Board, analog pixel signals scanned by CIS (B) are transmitted to AFEs
(IC2013 to IC2016) on the CENTER Board.

AFEs (IC2009 to IC2012) and AFEs (IC2013 to IC2016) converted the analog pixel signals to the digital.

The ASIC (F) (IC1011) receives front image signals from AFEs (IC2009 to IC2012) on the CENTER Board, and then
pre-processes them.
And the ASIC (B) (IC1013) receives back image signals from AFE (IC2013 to IC2016) on the CENTER Board, and then
pre-processes them.
(Pre-process means shading correction, line correction, and Dpi transformation.)

After finishing this, the ASICs (IC1011and IC1013) post-process the data into binary or compressed data,
and send it to the PC via USB Interface.
(Post-process means binary processing (simple binary, auto binary, dither, error diffusion), color, or gray scale
image processing (MTF, Color Correction, Gamma Correction, and others).)