Disclosed is a system, which divides a memory into a plurality of equally-sized sub-memories and controls an address of each sub-memory, thereby significantly increasing the access speed to an auxiliary memory unit, which includes a SCSI (Small Computer System Interface) controller for converting a format of data on a SCSI interface bus so that the data are accessed on a PCI(Peripheral Component Interconnect) interface bus for use in the system, a memory card module for storing data on the PCI interface bus therein, the memory card module being divided into a plurality of equally-sized memory blocks, and a CPU (Central Processing Unit) module for writing data on the PCI interface bus to the memory card module and reading out the data therefrom. The memory card module includes a PCI-to-memory controller, which is disposed between the PCI interface bus and the plurality of sub-memories as a bridge, for controlling access to the plurality of sub-memories, which is distributed in a hierarchical fashion.