Computer memory

  vacuum tubes

Memory is a state of information of computing system, as it kept active in some physical structure. Term memory is use for the information in physical system which are fast  as a distinction from physical system which are slow to access. Term memory is also refer to temporary state devices ,whereas the term storage is reserved for permanent data. Advance in storage technology nowadays have blurred the distinction of bits, memory kept on what is conventionally a storage system  called virtual memory.

Computer memory refer to physical devices use to store data or program (sequence or instruction)on a temporary or permanent basis for use in electronic digital computer. Computer represent information in binary code written as sequence of 0s and 1s. Each binary digit may be stored by any physical system that can be either in two stable state to represent 0 and 1. Such a system is called bi-stable. This could be an on-off switch. An electrical capacitor that can store or lose a charge, a magnet with its polarity up and down, or a surface that can have pit or not. Capacitor and transistor functioning as tiny electrical switch, used for temporary storage and either disk or tape with magnetic coating or plastic disc with pattern of pits are used for long-term storage.

Computer memory is usually refer to semiconductor technology that is used to store information in electronic devices. Primary computer memory make use of integrated circuit consisting of silicon based transistor. There are actually two main type of memory, volatile and non-volatile. Volatile memory is computer memory that require power to maintain the stored information. Current semiconductor volatile memory technology is usually either static RAM or dynamic RAM. Static RAM exhibit data remanence, but is still volatile since all data is lost when memory is not powered. Dynamic RAM allow data to be leaked and disappear automatically without a refreshing. Whereas non volatile memory is computer memory that can retain the stored information even when not powered. Example of nonvolatile memory include read only memory ,flash memory, most type of magnetic computer storage devices , optical disk and early computer storage method such as paper tape and punch card.