Canon FAX-L1000 - Manual (Page 217)

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FAX-L1000 Chapter 3: Technical Reference
2.6.7 Flow of image signals
a) G3 memory transmission
(1) The image is scanned by the contact sensor, and the analog image data is sent to the
SCNT board.
(2) The image processing IC (IC20) converts the analog image data from the contact sensor
into digital data.
(3) The digitized data is encoded by the CODEC IC in an MR with no compression
function, and transferred to DRAM (IC3) by high-speed DMA transfer.
(4) The main CPU (IC17) makes the transmission header, and encodes it with no
compression.
The main CPU software CODEC decodes the encoded data held in DRAM, and
converts MR -> run length -> MH/MR/MMR or MR -> raw data -> MH/MR/MMR/
JBIG.
(5) After being converted by an appropriate encoding method in the other party, a header is
added, and the data is sent to the DRAM transmission buffer.
(6) The main CPU reads the image data from the transmission buffer, and writes it to the
MODEM IC (IC26), then the MODEM IC sends it to the telephone line.
NOTE
G3 direct transmission
Direct transmission transfers image data by high-speed DMA transfer to
DRAM in the same way as memory transmission. Image data up to an image
memory block size of 16KB can be scanned. If the image file capacity
becomes full, the scanning operation is halted. When data is transmitted and
the image memory block emptied, the scanning operation begins again.