Canon iR5055 Series Service Manual page 123

- Self Diagnosis Program (interval 1)
The self-diagnosis program is run by the CPU on the main controller PCB when the main power switch is turned on.
The program is used to check the condition of the image memory (SDRAM) and the HDD.
The machine will indicate an error code if it finds a fault while running the program.
- Boot Program (interval 2)
When the self-diagnosis program ends normally, the CPU on the main controller PCB executes the boot program.
The program is used to read the system software from the HDD to write it into the image memory (SDRAM).
- Image Memory (SDRAM) Area (interval 3)
The system software written by the boot program initializes the various functional blocks (e.g., I/F settings of the main controller).
When all the foregoing ends normally, the machine becomes ready to accept a job (i.e., the control panel shows the Operation screen, and the LED on the Start key
changes from red to green).
1
- While the Self-Diagnosis Program Is Being Executed
Image memory (SDRAM)
System Image data
area
CPU
Self diagnosis
program
program
BootROM
Main controller PCB
: access to the program during execution
: access for checking
Progress bar
2 3
F-4-6
area
HDD
Boot
F-4-7
Chapter 4
4-5