A memory that has no moving parts and in which the read and write operations are entirely electronic. The earliest forms of electronic memory employed thermionic valves in the memory cells. These were replaced by the much smaller and cheaper ferrite cores, which consumed very much less power. These in turn have been superseded by solid-state memories that are extremely versatile high-speed low-power devices: the growth of microelectronic techniques has made possible the production of semiconductor memories of large memory capacity and extremely small physical size.