Files and mass storage

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MASS STORAGE

A mass-storage device, a nonvolatile medium, organized collections, space requirements, change the locations of data, without regard, a card catalog, a physical location, prior records, ascending sequence, speed up access to, sequentially, organize alphabetically, store sequentially, within the file.

ascending order- зростаючий порядок

ascending sequence - зростаючa послідовність

designate (v) – позначати; визначати

direct-access file - файл прямого доступу

directory (n) – каталог

field(n) - поле

index(n) - індекс

index-sequential (adj) - індексно-послідовний файл

key field - поле ключа

maintain(v) - обслуговувати

mass storage - запам'ятовуючий пристрій великого обсягу

multilevel index - багаторівневий індекс

record (n) – запис; (v) - записувати

retrieve data - відновлювати

sequential (adj) – послідовний

The term mass storage is derived from the term mass data, which means a quantity of data larger than the amount storable in the memory of a computer at any one time. The purpose of a mass-storage device is to provide a permanent or nonvolatile medium for information so that it can be stored, retrieved, and manipulated. In effect, mass storage provides a place to store data and programs before and after processing. Data or information is always grouped together in organized collections called files, which often consist of records and fields. The operating system takes care of the details of storing and maintaining the files in a mass-storage device. For example, the operating system is free to change the location of data as space requirements on the device may dictate.

Operating systems support three basic types of files: sequential, index-sequential, and direct-access.

Sequential files can only be accessed from beginning to end sequentially. For example, to read or write the last record in the file, you must first read or write all previous records. As an analogy, think of a series of songs recorded on an audiocassette. Each song is stored sequentially, one after the other, and can only be accessed in sequential order. As a general rule, sequential files are sorted into an order: most often in ascending order, that is, starting with the lowest value and proceeding to the highest value. A variation of the sequential method is called index-sequential. An index-sequential file is one in which an index is created to speed up access to records within the file. To access a record in an index-sequential file, you first consult an index. Large index-sequential files multilevel indexes Direct-access files allow you to read or write any record in the file without regard to its location. Direct-access files require that you designate one of the fields to be a key field that denotes the record’s position in the file. A disk can be used to store and retrieve data in a sequential, index-sequential, or direct manner, but magnetic tape can only be used to store and retrieve data in a sequential manner.

1.4 Give English equivalents of the following words and word-combinations:

Iндекс, засіб, розміщення, розташувати у зростаючому порядку, незалежно від його розміщення, багаторівневі індекси, файл послідовного доступу, розміщення фізичного запису, файл прямого доступу, визначити одне з полів як поле ключа, від найменшого значення до найвищого, розташувати у спадному порядку, поле, запис, енергонезалежний засіб, зберігати дані, в алфавітному порядку, послідовно, знаходити дані.

Дата добавления: 2015-01-03