Disk storage control device including a sector number register and range detection circuitry for reading and writing to a range of detectors

摘要

An external memory control device which is capable of reducing the time required for processings such as write and read of data for the storage areas of an external memory device, such as a disk, is disclosed. The external memory control device includes a smallest sector number register and a largest sector number register which store the smallest and the largest sector numbers, respectively, within a processing range on a track that is designated by a processing request signal frokm a central processing unit, and a processing range detecting part which detects whether a sector number read from the designated track is within the processing range. In this external memory control device, if the sector number read from the designated track is within the processing range, the processings start from the next sector, so that waiting until the arrival of the smallest sector number is no longer needed, and the time required for processing per track can be reduced.