Data processing system including a data storage control unit

A control system for a data store comprising a plurality of storage modules, only one of which is shown in the drawings, includes an input register 20, an output register 24 and a re-configurable table system 10. Storage addresses are received by the input register. The address bits defining the upper boundaries of the basic storage modules are applied to the table system, which in response thereto applies pre-determined upper boundary bits to the output register, which also receives the remaining address bits from the input register to form a new storage address. Thus, in accordance with the content of the table absolute addresses from the devices requiring access to the storage system are converted to addresses in basic storage modules selected by the table.