How Does a Memory Cache Speed Up Computer Processing?

A cache, which is a high speed data storage device, is where a microprocessor stores that data it uses most often. Just like you put your kitchenware on the kitchen table when you are dining, a computer puts the data it needs to use for a specific application in its cache. If a new applications arises that requires heavy use of different data, a microprocessor will bring new data into the cache memory so it can perform the tasks that require this data more efficiently.

Computer memory is designed in a hierarchy. Each module of the hierarchy is categorized according to how long it takes to access data from a specific type of memory module. It takes the least amount of time for a micrprocessor to access data from cache memory. Main memory, most often built with DRAM memory chips,takes longer to access data than cache memory. Flash memory, built with Flash memory chips, will take even longer, while data on a disk drive, often called virtual memory, will take the longest of all.

A processor's clock speed determines the maximum rate at which processors can execute instructions. Cache memory chips, because they are designed to deliver instructions or data as fast as the microprocessor can utilize them, permit microprocessors to run at full speed. If the instructions and data are in the cache and not in main memory or disk drive memory, the processor can perform at its maximum specified processor clock speed.

All computers use memory management algorithms that store data and instructions such that the data and instructions that are used most often can be accessed in the fastest way possible. If a computer has cache memory, the microprocessor will put the data and instructions it calls on the most often in high speed cache memory. The microprocessor's memory cache algorithm tags data and instructions with data bits that it uses to determine which data and instructions are used most often. The cache algorithm also transfers data and instructions from the cache that are no longer heavily used to slower speed main memory.

The size of high-speed cache memory is a major factor in the determination of how much the speed of the computer will increase. Because they can can store a lot more data in their high speed memories, very large caches improve computer processing speed much more than smaller caches. However, there is a point of diminishing returns: At some point, the larger cache no longer offers a gain in processing speed that will offset the high price tag of a larger cache memory.