Patent ID: 8027595

Claim:
A method of storing information on an amount of used toner, the method comprising: determining whether a customer replaceable unit monitor (CRUM) memory to store information on an amount of used toner is included in a cartridge of an image forming device each time a cartridge is installed in the image forming apparatus; storing the information on the amount of used toner in a non-volatile memory of the image forming device each time the CRUM memory is not included in the installed cartridge of the image forming device; and storing the information on the amount of used toner in the CRUM memory each time the CRUM memory is included in the installed cartridge, wherein the cartridge having no CRUM memory is installed in the image forming apparatus when the image forming apparatus was manufactured, and wherein the cartridge having no CRUM memory is able to be installed back in the image forming apparatus when the toner remaining in the cartridge is not below a threshold amount.