Patent ID: 8218980

Claim:
An image forming device comprising: a main body; a replaceable unit configured to be detachably mounted in the main body; a processor configured to execute instruction units including: a determination unit that determines whether the replaceable unit mounted in the main body is a genuine product or a non-genuine product; a first control unit; and a second control unit; a first memory mounted in the main body, the first memory being configured to store a physical value changing with a usage of the genuine product in the main body; a second memory mounted in the main body, the second memory being configured to store the physical value changing with usage of the non-genuine product in the main body; a temporary memory mounted in the main body, the temporary memory being configured to temporarily store the physical value changing with the usage of the non-genuine product in the main body, wherein the first control unit is configured to count the physical value on the first memory, if the determination unit determines that the replaceable unit mounted in the main body is the genuine product, and wherein the second control unit is configured to count the physical value stored on the temporary memory if the determination unit determines that the replaceable unit mounted in the main body is the non-genuine product, and to store the physical value stored in the temporary memory onto the second memory if the physical value in the temporary memory reaches a predetermined value.