COPYRIGHT © 1999 CANON INC. CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)B. Drum Cartridge MemoryThe drum cartridge memory (EEPROM) contains two areas: ROM area and RAMarea. The ROM area retains an ID code specific to the drum cartridge, and is used exclu-sively for reading. The DC controller PCB reads the ROM area of the drum cartridgewhen the power switch is turned on or the cover is closed to check if the correct cartridgeis set.The RAM area allows both reading and writing, and the DC controller PCB reads fromthe drum cartridge memory at specific timing to check the presence/absence or the lifeof the drum cartridge.The timing at which the DC controller PCB reads and writes data stored in the RAMarea of the drum cartridge is as follows:Reading• When the power switch is turned on.• When the cover is closed.Writing• When the power is turned off.• When the cover is opened.• At the end of printing (in the case of continuous printing, at the end of continuousprinting, or at the end of jam removal).The copier remembers a fault, if any, in the drum cartridge at time of reading/writ-ing. If writing fails (or reading fails three times consecutively), i.e., an error checksum, the DC controller PCB communicates the fact to the printer board*1 as a drumcartridge memory fault.* 1 Reader controller PCB (when making copies with the reader unit installed).CHAPTER 4 IMAGE FORMATION SYSTEM4-6Download free service manual at http://printer1.blogspot.com
