Transmited light micrograph of a extended data-out dynamic random-access memory (EDO DRAM) module (capacity 64 MB, timing 60 ns access). Random-access technology allows the CPU to read and write data very quickly. The information therein is accessed randomly. This addressable semiconductor memory device of solid-state volatile memory, with its EDO page mode access cycle, allows the CPU to perform faster data operations: read, write, or read-modify-write. Organized into several million memory cells (a capacitor and a transistor per unit), each one may store a binary digit, or bit. To preserve the information, a periodic refresh of written data is required. Nevertheless, the chip can reach very high densities of storage and is therefore generally used as the main memory in personal computers. It is by far the most widely used RAM. Field of view size: 148 x 222 痠 (0.006 x 0.009 in)