ЛПР №2 Робота з англомовними джерелами.
Базова лексика до заняття
CD ROM (compact disk read-only memory) – постійна пам’ять на
компакт-диску
DVI (digital video interactive) – цифровий відеоформат
WORM (write-once, read mostly) – оптичний диск (разового запису і багаторазового читання)
magnetic medium – магнітний носій
density limitation – обмеження за щільністю
concentric (adj) – концентричний
access speed – швидкість доступу
complement – доповнювати
compression technique – техніка (метод) ущільнення
real-time – реального часу
seek time – тривалість установлення (головки)
reverse polarity – змінити полярність (на протилежну)
file server – файловий процесор
storage unit – запам’ятовувальний пристрій (блок)
indelible – такий, що не стирається
large-scale integration – велика інтеграція
1. Прочитайте та пекладіть текст.
Files and Mass Storage
The term mass storage is derived from the term mass data, whichmeans a quantity of data larger than the amount storable in the memory of acomputer 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 bestored, retrieved, and manipulated. In effect, mass storage provides a placeto store data and programs before and after processing.
Data or informationare 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 songsrecorded on an audiocassette. Each song is stored sequentially, one after theother, 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, startingwith the lowest value and proceeding to the highest value. A variation of thesequential 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 accessa 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 writeany record in the file without regard to its location. Direct-access files requirethat you designate one of the fields to be a key field that denotes the record’sposition 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 storeand retrieve data in a sequential manner.
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