Canon MultiPASS C50 Service Manual page 243

2.3 Data Flow
1) Interface
Character codes, control codes, and image data conforming to the printer's character table are sent to the
interface from the computer. The data are received when the printer is in on-line standby, or when the
carriage changes directions during printing.
2) Input buffer
Data received from the interface are stored in the printer DRAM's built in input (reception) buffer.
3) Data analysis and printer buffer
The MPU analysis the data stored in the input buffer, and printing image data for each nozzle of the BJ
cartridge are stored in the printer DRAM's built-in print buffer.
If there are character data, the Control/CG ROM font image data are stored in the print buffer. Control
codes are used for switching print modes, etc. The image data are already formatted for each nozzle of
the BJ cartridge, and are stored as is in the print buffer.
4) Printing
When control codes with a CR/LF, etc, print start function are processed, and the print buffer becomes
full, the image data stored in the printer buffer are sent to the BJ cartridge and printed out.
Character "BJ"
Image " "
Character Code: "B" = [ 42 ] Hex.
Character Code: "J" = [ 4A ] Hex.
Control Code: ESC * <m> <n> <d> (Select Image Graphics Mode)
= [ 1B ] Hex., [ 2A ] Hex., <m>, <n>, <d>
Image Data:
Input Buffer
(DRAM)
Character Code
[ 42 ] [ 4A ] [ 1B ] [ 2A ] <m> <n> <d> [
Font Image
Data (ROM)
01234
@ABCD
Selected Font
Image Data
B J
Figure 2-2 Data Flow (image)
2-3
Chapter 2: Technical Reference
Control Code
Select Image
Graphics Mode
Print Buffer
(DRAM)
BJ
Image data
image data
Image Data
BJ Cartridge