Computer Memory

Computer Memory: Who Is Smarter, You Or Your Computer?

There are several different types of memory a computer can have. Read only memory, or ROM, is a class of storage media used in computers and other electronic devices. Random access memory, usually known by its acronym, RAM, refers to data storage formats and equipment that allow the stored data to be accessed in any order. In contrast, other types of memory devices, such as magnetic tapes, disks, and drums, can access data on the storage medium only in a predetermined order due to constraints in their mechanical design. Molecular memory stores information in polymers that can store electric charge. Molecular memory might be especially suited for primary storage.

Main memory contains the programs that are currently being run and the data the programs are operating on. The arithmetic and logic unit can very quickly transfer information between a processor register and locations in main storage, also known as a memory addresses. In modern computers, electronic solid state random access memory is used for main storage, and is directly connected to the CPU via a memory bus and a data bus. The memory bus is also called an address bus or front side bus and both busses are high speed digital superhighways. Access methods and speed are two of the fundamental technical differences between memory and mass storage devices. All memory sizes and storage capacities will inevitably be exceeded with advances in technology over time.

Cache memory is a special type of internal memory used by many central processing units to increase their performance or throughput. Some of the information in the main memory is duplicated in the cache memory, which is slightly slower but of much greater capacity than the processor registers, and faster but much smaller than main memory. Multi level cache memory is also commonly used. Primary cache is the smallest, fastest and closest to the processing device. Secondary cache is larger and slower, but still faster and much smaller than main memory.

Semiconductor memory uses semiconductor based integrated circuits to store information. A semiconductor memory chip may contain millions of tiny transistors or capacitors. Both volatile and non volatile forms of semiconductor memory exist. In modern computers, primary storage almost exclusively consists of dynamic volatile semiconductor memory or dynamic random access memory. Since the turn of the century, a type of non volatile semiconductor memory known as flash memory has steadily gained share as offline storage for home computers. Non volatile semiconductor memory is also used for secondary storage in various advanced electronic devices and specialized computers.

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