Canon LBP-860 Service Manual page 74

CHAPTER 2
b. Banding Coprocessor
The banding coprocessor is an Intel
8296 1 KU printer coprocessor that
integrates a graphics accelerator and
compression processor necessary for
complex page description language
necessary system control for the CPU to
has the following main functions:
The Generic Array Logic device (GAL11
generates DRAM RAS control signals
under direction from the 82961KD.
The Conlroller contains two banks
board, and two 72.pin DRAM SIMM
modules. Each SIMM module can
contain 1. 2. 4. 8. 16 or 32 MBytes of
print data. video data, fonls, and
variable data used for program control.
d. ROM
Page Mode ROM and two 72.pin KOM
SIMM modules. The Page Mode ROM
may be 2 or 4 MBytes. The two SIMM
modules may be from 1 to 16 MBytes.
ROM is used for storing the Controller's
program and font data.
e. EEPROM
The 2 KBit serial EEPROM is provided
for non-volatile storage of the printing
environment, number of prints, and so
on.
f. Serial Controller
The NS16550A Serial Controller is used
as the interface to the Host serial
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port for printer data.
interface.
Parallel Port Interface
A 256 byte FIFO is used to buffer
printer data from the Host parallel port.
parallel port interface. The Generic
Array Logic device (GAL21 controls the
transfer of printer data over the Host
parallel port.
Engine Interface
The engine interface, both video signal
generation and print engine communi-
cation. is controlled by the 82961KD
device.
Video Logic
Logic is provided to select the video
c l o c k f r e q u e n c y s u p p l i e d t o t h e
82961 KD 8X PLL cicuit. Selections are,
59.64024 MHz clock for 600 x 600
resolution. 14.910506 MHz clock for
300 x 300 resolution, or an external 1X
clock for 1200 x 1200 resolution.
External Video
The connector J 140 is provided to
support video post processing features
such as resolution enhancement or
resolution doubling. In addition, it can
be used to provide clocks not provided
by controller, supporting non standard
print engine resolutions.
1.
The external I/O Slot (connector 5172)
supports user installed Host I/O
controllers such as AppleTalk and
Ethernet. An 80.pin connector is used
to interface to the 8096OKB
LAD bus. In addition, this connector
provides for the addition of a video
adapter interface that allows for
superimposed video on the existing
video data supplied by the 82961KD.
processor