Image forming apparatus, replacement assembly for image forming apparatus and integrated circuit chip therefor

The present invention provides an electro photographic image forming apparatus comprising a replacement assembly having a toner container (2) attachable to the image forming apparatus, a feeding unit to feed toner from the toner container to a development unit, and a read/write non-volatile memory (21), wherein, the image forming apparatus comprising an estimation unit which generates information in such way that first, the estimation unit obtains an amount of a toner feed period for the feeding unit during forming images, next, accumulates the amount of a toner feed period into an accumulated sum of the amount of a toner feed periods, then, generates the information on the amount of toner in the replacement assembly and stores the information in the read/write non-volatile memory (21).