System for addressing a data storage unit used in a computer

A system for addressing a data storage unit used in at least one of server and client computers, which comprises:

• means for converting a format of data on an external bus such that the data are accessed on an internal bus for use in the system;
• a memory card module connected to the internal bus for storing data transmitted through the internal bus, wherein the memory card module includes a plurality of memory modules each having a plurality of equally-sized memory blocks, each memory block being divided into a predetermined number of equally-sized sub-memories such that the memory module has a hierarchical memory configuration, wherein the memory card module includes a PCI-to-memory controller, which is disposed between the internal bus and the memory module as a bridge, for controlling access to the plurality of sub-memories, and
• wherein the PCI-to-memory controller includes:
• a PCI interface controlling unit for performing a standard PCI command, control and data signal processing, the PCI interface controlling unit including a register block having a lower address bit, an upper address bit and a select bit, wherein the lower address bit represents addresses included in the range of an address region within a memory map, the upper address bit represents an address set to be used when a memory address region is beyond the address region of the memory map, and the select bit is used to directly access the memory module;
• and
• a plurality of memory controlling units for performing a direct read/write operation for the sub-memories in response to the PCI command from the PCI interface controlling unit;
• and
• means for writing data on the internal bus to the memory module and reading out the data therefrom.