Canon LBP-800 Manual Do Serviço

A. Interface Controller PCB
1. Outline
The interface controller receives print information from external devices such as host comput-
ers through interface cables.

Print information described above is dot data converted from print data, corresponding to the

resource type, in the host computer.

The dot data is then passed to the engine controller to control the laser diode emitting.
The external devices can check the printer status using bi-directional interface.
The location of the interface controller is shown in Figure 2-6-1, and the block diagram in

Figure 2-6-2.

2. Function of Blocks
a. CPU (IC1)
The main functions of CPU (IC1) are:
1) To control the video interface and parallel interface (Centronics specification.)
2) To process the serial commands of the video interface.

b. DRAM (IC2)
DRAM has a memory capacity of 512 KB and stores the following information:
1) Dot data converted from the image data. (Receive buffer)

c. Cellbase IC (IC3)
The main functions of Cellbase (IC3) are:
1) To control the input/output of the DRAM with a built-in interface controller.
2) To control the timing of sending the dot pattern data to the engine controller.
3) To process the image such as smoothing, halftone and so on.