RandomAccessMemory

RandomAccessMemory (RAM) is a form of computer memory that allows data to be read or written in roughly the same time, regardless of its location. It serves as the system's short-term, volatile storage, holding the instructions and data the CPU uses. RAM loses its contents when power is removed, unlike non-volatile storage such as flash memory or disk drives.

RAM generally comprises dynamic RAM (DRAM) and static RAM (SRAM). DRAM stores each bit as charge on a capacitor and requires refreshing, making it dense and inexpensive. SRAM uses flip-flops to hold bits, does not need refreshing, and is faster and more costly, used for cache memory.

Modern RAM follows standards such as SDRAM and DDR generations (DDR4, DDR5). Modules come as DIMMs for desktops and servers, or SO-DIMMs for laptops. Servers may use ECC memory to detect and correct errors; consumer systems typically use non-ECC memory.

RAM capacity is measured in bytes, typically gigabytes for personal computers. Performance depends on capacity, speed (MHz or MT/s), and latency. RAM sits between CPU caches and persistent storage in the memory hierarchy; data transfer is managed by a memory controller.

Because RAM is volatile, data must be reloaded from non-volatile storage after power loss. RAM size and speed influence system responsiveness and multitasking. Upgrading usually means installing higher-capacity or faster RAM compatible with the motherboard.