Apparatus for enabling exchange of data of different lengths between memories of at least two computer systems

An apparatus for use in combination with a main memory for memorizing main data and a cache memory for memorizing selected data of said main data, said apparatus comprising:

• judging means connected to said cache memory for judging whether or not a desired data of said main data is memorized as one of said selected data in a particular address of said cache memory, said judging means passing a cache access signal when said desired data is not memorized in said particular address;
• a supplementary memory including a first register for memorizing a data base address representative of a first address in said main memory and a second register for memorizing a tag base address representative of a second address in said main memory,
• accessing means connected to said supplementary memory, said judging means, and said main memory for accessing said main memory in accordance with said data base address, said tag base address and said cache access signal to read from said main memory a data part of said main data and a tag part of said main data collectively as a specific data of said main data being said desired data;
• and
• storing means connected to said accessing means and said cache memory for storing said specific data from said accessing means in said particular address;
• wherein said accessing means comprises:
• processing means connected to said first register, said second register, and said judging means for processing said data base address and said tag base address with reference to said cache access signal into a first and a second address signal, respectively;
• and
• reading means connected to said processing means and said main memory for reading said data part and said tag part from said main memory in accordance with said first and second address signals.