RandomAccess

Random access refers to the ability to read or write data at any position in a storage medium with roughly the same time, independent of the location. This contrasts with sequential access, where data must be read in order. Random access is a defining feature of random-access memory (RAM) and is a common property of modern storage architectures that expose direct addressing.

In RAM, each storage cell has a unique address; the memory controller can select a cell and perform a read or write operation. Access time is typically constant relative to address size and dominated by technology-specific latency and bus bandwidth. This enables efficient data structures like arrays, and supports multitasking by allowing arbitrary memory access patterns.

In storage devices, random access describes the ability to seek to and read data from any block. Hard disk drives provide random access through mechanical movement, which introduces seek and rotational latencies; solid-state drives remove most mechanical latency, achieving near-instant random access. Magnetic tapes, by contrast, are naturally sequential.

In software and systems, random access is exploited by data structures such as arrays, hash tables, and random-access files, where the program can jump to an offset or index without linear scanning. Operating systems and databases rely on random access to manage memory, page tables, caches, and indexed storage.

Challenges associated with random access include cost of misses in caches, memory fragmentation, and the difference between uniform access time in ideal RAM and real hardware where latency varies with location and contention.