control block - определение. Что такое control block
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Что (кто) такое control block - определение

DATA STRUCTURE USED FOR FILE ACCESS IN CP/M, MS-DOS AND COMPATIBLE OPERATING SYSTEMS
File control block; Disk Transfer Area

File Control Block         
A File Control Block (FCB) is a file system structure in which the state of an open file is maintained. A FCB is managed by the operating system, but it resides in the memory of the program that uses the file, not in operating system memory.
file control block         
<operating system> (FCB) An MS-DOS data structure that stores information about an open file. The number of FCBs is configured in CONFIG.SYS with a command FCBS=x,y where x (between 1 and 255 inclusive, default 4) specifies the number of file control blocks to allocate and therefore the number of files that MS-DOS can have open at one time. y (not needed from DOS 5.0 onward) specifies the number of files to be closed automatically if all x are in use. (1995-03-21)
Task Control Block         
INSTANCE OF A PROCESS CONTROL BLOCK WITHIN IBM OS/360 AND SUCCESSOR SYSTEMS
Request Block
<architecture> An MVS control block used to communicate information about tasks within an address space that are connected to an MVS subsystem such as MQSeries for MVS/ESA or CICS. {FAQ (http://www-4.ibm.com/software/ts/mqseries/library/manuals/csqfao/CSQFAO22.HTM)}. (2000-12-30)

Википедия

File Control Block

A File Control Block (FCB) is a file system structure in which the state of an open file is maintained. A FCB is managed by the operating system, but it resides in the memory of the program that uses the file, not in operating system memory. This allows a process to have as many files open at one time as it wants, provided it can spare enough memory for an FCB per file.

The FCB originates from CP/M and is also present in most variants of DOS, though only as a backwards compatibility measure in MS-DOS versions 2.0 and later. A full FCB is 36 bytes long; in early versions of CP/M, it was 33 bytes. This fixed size, which could not be increased without breaking application compatibility, led to the FCB's eventual demise as the standard method of accessing files.

The meanings of several of the fields in the FCB differ between CP/M and DOS, and also depending on what operation is being performed. The following fields have consistent meanings:

The 20-byte-long field starting at offset 0x0C contained fields which (among others) provided further information about the file:

Further values were used by newer versions of DOS until new information could no longer fit in these 20 bytes. Some preceding "negative offset" bytes were squeezed from reserved spaces in CP/M Zero Page and DOS Program Segment Prefix for storing file attributes.