Cache device and method for storing tag data and cache data in cache device

A method for, in a cache device comprising a compressing/decompressing portion including a compressor and a decompressor, a tag/data memory capable of storing a plurality of pieces of tag data and a plurality of pieces of compressed cache data corresponding to the plurality of pieces of tag data, and a controlling portion, storing the pieces of tag data and the pieces of cache data, the method comprising:

• adding first information to a piece of tag data read last when storing the pieces of tag data and the pieces of cache data into a storage area of the tag/data memory, the first information indicating that the piece of tag data read last is a last piece of tag data;
• storing the pieces of cache data compressed by the compressor into the storage area;
• adding second information indicating that each of the stored pieces of cache data is compressed, to a corresponding piece of tag data;
• and
• decompressing the compressed pieces of cache data by the decompressor and outputting the pieces of cache data to a master apparatus connected to the cache device.