| 翻訳と辞書 |
| Direct access storage device ： ウィキペディア英語版 |
Direct-access storage device
A direct-access storage device (DASD, pronounced ) is any secondary storage device in which "each physical record has a discrete location and a unique address." IBM developed DASDs for use with mainframe computers and some minicomputers. Disk drives, magnetic drums, data cells and optical disc drives are all classified as DASDs.
Access methods for DASDs include ''sequential'', ''indexed'', and ''direct''. The ''direct access'' capability, occasionally and incorrectly called ''random access'' (although that term survives when referring to memory or RAM), stands in contrast to ''sequential access'' used in tape drives. A record on a DASD can be accessed without having to read through intervening records from the current location, whereas reading anything other than the "next" record on tape requires skipping over intervening records, and requires a proportionally long time to access a distant point in a medium.
The DASD ''storage class'' includes both fixed and removable media.
==Architecture==
IBM mainframes access I/O devices through ''channels'', a type of subordinate mini-processor. ''Channel programs'' write to, read from, and control the given device.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Direct-access storage device」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|