1. A method for integrating at least one imperfect semiconductor memory device in a data processing apparatus, the method which comprises: assigning an operating address range to the semiconductor memory device; assigning defect addresses in the operating address range to defective memory cells of the semiconductor memory device; storing the defect addresses in a defect memory; before an instruction processing unit of the data processing apparatus accesses an address in the operating address range, comparing the address to be accessed with the defect addresses; and if the address to be accessed corresponds with one of the defect addresses, recoding the address to be accessed to a replacement address.