Although the most common type of computer memory is random access memory (RAM), there are many other types of memory that can be used on a computer. These include cache memory, flash memory, and file storage. Memory architecture refers to the combination of different types of memory to balance the performance of a computer without compromising reliability of storage or making the computer cost-prohibitive. In general, the different types of memory function on a hierarchy ranging from fast and expensive to slower and less inexpensive. Memory architecture works to ensure that the computer has a blend of all types of memory, keeping the computer's hardware as balanced and cost-efficient as possible.
In addition to differing based on cost and speed, memory also differs based on permanence. Standard RAM in a computer is a dynamic form of memory, which means that it only retains information as long as the computer remains powered on. This presents an obvious problem when it comes to keeping information on the computer following a power on-off cycle, as without a more persistent form of memory, all information on the computer would be lost in the event of a power failure. File storage memory within the computer — the most common example of this is a hard drive — provides a relatively slow but stable method for keeping information on the computer past shutdown.
The processor registers and cache memory are generally the fastest and most expensive. By locating these types of memory on the physical processor chip, the transfer time and latency for these types of memory is extremely small. This means that information can travel to and from these types of memory in the blink of an eye, making them efficient for holding information and variables while the processor is actively working on a specific problem.
RAM is at the next level, both cheaper and slower than processor registers and cache memory. This is connected to the processor via the front side bus, which means that latency increases while speed decreases when compared to register and cache memory. Cost decreases substantially as well, making RAM the most cost-efficient form of dynamic storage in the memory architecture.
Finally, virtual memory and file storage locations are both generally kept on the hard drive. Virtual memory is a section of the hard drive that the computer's operating system treats as RAM. Hundreds and hundreds of gigabytes of hard drive storage can be purchased for the same amount as just four to eight gigabytes of RAM, making it the best persistent mass storage location on a computer's memory architecture.