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Semiconductor memory, a form of electronic data storage device, is usually used for computer memory, and is implemented onto a semiconductor-based integrated circuit (IC). There are many types of devices that use semiconductor memory, including flash memory (or flash ROM), Read-Only Memory (ROM), and Magnetoresistive Random Access Memory (MRAM). All of these kinds of semiconductor memory are non-volatile memory, meaning that the contents of memory stored in the devices are kept even when the computer has been shut down. Volatile memory like Dynamic Random Access Memory (DRAM) or Static Random Access Memory (SRAM) can also be semiconductor based. The difference between non-volatile memory and volatile memory is that the latter must have a constant electric flow to keep stored information.
ROM is just one of many types of semiconductor-based computer memory that can just be read and not written. Its uses include having permanent memory without a flow of electricity and security of sensitive data against malicious viruses. ROM stores common programs in a computer’s system for constant and consistent availability. The most used and most common program stored in ROM is the Basic Input/Output System (BIOS) program. It is in the ROM so that a computer can boot up its operating system.
Flash memory, or simply flash, is another type of semiconductor memory found in computers as well as smart phones, MP3 players, Global Positioning System (GPS) devices, Universal Serial Bus (USB) drives and digital cameras. Since devices like these are portable and subject to losing electric power, having flash memory is beneficial because any memory stored will be kept in any circumstance. Flash memory can erase whole blocks of data, rather than by individual bytes, and is found in devices that use applications that require constant updates. Memory cards and USB drives use flash because of the fast rate of transferring information and high capacity of information storage. These devices can also have hardware encryption that’s built in for the purpose of password protection.
Another type of semiconductor memory is RAM, which is volatile and can be both written and read. There are different kinds of RAM, notably SRAM and DRAM. The two differ in that the former stores data while electric power is running and the latter needs refreshment of electrical charge every couple of milliseconds. SRAM takes less power and is faster than DRAM, but is expensive to construct and has less storage capacity. DRAM has greater storage capacity and is therefore more commonly used for computer memory.