[ The PC Guide | Systems and Components Reference Guide | Motherboard and System Devices | System Cache | Function and Operation of the System Cache ]

The level 2 cache is comprised of two main components. These are not usually physically located in the same chips, but represent logically how the cache works. These parts of the cache are:

• The Data Store: This is where the cached information is actually kept. When reference is made to "storing something in the cache" or "retrieving something from the cache", this is where the actual data goes to or comes from. When someone says that the cache is 256 KB or 512 KB, they are referring to the size of the data store. The larger the store, the more information that can be cached and the more likelihood of the cache being able to satisfy a request, all else being equal.
• The Tag RAM: This is a small area of memory used by the cache to keep track of where in memory the entries in the data store belong. The size of the tag RAM--and not the size of the data store--controls how much of main memory can be cached.

In addition to these memory areas are of course the cache controller circuitry. Most of the work of controlling the level 2 cache on a modern PC is performed by the system chipset.

Next: Structure of the Data Store

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