Random access

In computer science, random access (sometimes called direct access) is the ability to access an arbitrary element of a sequence in equal time. The opposite is sequential access, where a remote element takes longer time to access. A typical illustration of this distinction is to compare an ancient scroll (sequential; all material prior to the data needed must be unrolled) and the book (random: can be immediately flipped open to any random page. A more modern example is a cassette tape (sequential—you have to fast-forward through earlier songs to get to later ones) and a compact disc (random access—you can jump right to the track you want). The term random access memory (RAM), however, is used for semiconductor chip memory circuits used in computers. (The term was also used to describe ferrite-core memory in early computers).

In data structures, random access implies the ability to access the "N"th entry in a list of numbers in constant time. Very few data structures can guarantee this, other than arrays (and related structures like dynamic arrays). Random access is critical to many algorithms such as quicksort and binary search. Other data structures, such as linked lists, sacrifice random access to make for efficient inserts, deletes, or searches.


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  • Random Access —   [engl.], wahlfreier Zugriff; vgl. Zugriff. und RAM …   Universal-Lexikon

  • random access — ► NOUN Computing ▪ the process of transferring information to or from memory in which every memory location can be accessed directly rather than being accessed in a fixed sequence …   English terms dictionary

  • random-access — ☆ random access [ran′dəm ak′ses ] adj. Comput. designating or of a volatile memory that allows data to be accessed directly and does not require following a sequence of storage locations …   English World dictionary

  • Random access — Unter Wahlfreiem Zugriff (engl. random access, auch direkter Zugriff, Direktzugriff) wird in der Informatik die Möglichkeit verstanden, in konstanter Zeit einen Speicherzugriff auf ein beliebiges Element eines Datenspeichers oder einer… …   Deutsch Wikipedia

  • random access —    Describes the ability of a storage device to go directly to the required memory address without needing to read from the beginning every time data is requested.    In a random access device, the information can be read directly by accessing… …   Dictionary of networking

  • random access — 1. the capacity of a videodisc or compact disc player that allows the user to select and replay any portion without starting at the beginning. 2. availability, as of a service or facility, whenever needed or desired: an executive s need for… …   Useful english dictionary

  • random-access — ¦ ̷ ̷  ̷ ̷ ¦ ̷ ̷ ˌ ̷ ̷ adjective : permitting access (as to stored information) in any order the user desires random access capability of a videodisc player * * * /ran deuhm ak ses/, adj. Computers. 1. of or pertaining to a storage medium in… …   Useful english dictionary

  • random access — laisvoji prieiga statusas T sritis informatika apibrėžtis Tiesioginė ↑prieiga prie duomens, neperžiūrint kitų duomenų. Kreipties trukmė nepriklauso nuo duomens vietos tarp kitų duomenų. atitikmenys: angl. direct access; random access ryšiai: dar… …   Enciklopedinis kompiuterijos žodynas

  • random access — 1. the capacity of a videodisc or compact disc player that allows the user to select and replay any portion without starting at the beginning. 2. availability, as of a service or facility, whenever needed or desired: an executive s need for… …   Universalium

  • random-access — adjective Capable of being accessed in any order, not required to be sequential. See Also: random access memory …   Wiktionary


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