In the Open Systems Interconnection (OSI) communications model, the physical layer supports the electrical or mechanical interface to the physical medium. For example, this layer determines how to put a stream of bits from the upper (data link) layer on to the pins for a parallel printer interface, an optical fiber transmitter, or a radio carrier.
DEFINITION of sector
On a computer diskette or hard disk, a sector is one of the “pie slices” the diskette or disk is divided into. Dividing the circular medium into pie slices is a way to organize it so that data can be located by the read/write heads of the drive. The diskette or disk is also divided into a number of concentric circles. Data can be located
DEFINITION of root directory
In a computer file system that is organized as a hierarchy or tree, the root directory is the directory that includes all other directories. (Unlike a real tree, a tree file system has only one root!) In UNIX-based as well as in other operating systems, the root directory has no name. It is simply represented by the special character that separates directories in a file system.
DEFINITION of Resilient File System
ReFS (Resilient File System) is a file system designed for next-generation operating systems, such as Windows Server 8. ReFS combats bit rot (the corruption of bits in a file system over time) through disk scrubbing tasks that read and validate data. It maintains a high level of compatibility with NTFS and builds on that foundation
DEFINITION of queue
In general, a queue is a line of people or things waiting to be handled, usually in sequential order starting at the beginning or top of the line or sequence. In computer technology, a queue is a sequence of work objects that are waiting to be processed. The possible factors, arrangements, and processes related to queues is known as queuing theory.
DEFINITION of encryption
Encryption is the conversion of data into a form, called a chipertext, that cannot be easily understood by unauthorized people. Decryption is the process of converting encrypted data back into its original form, so it can be understood.
DEFINITION of FDDI
FDDI (Fiber Distributed Data Interface) is a set of ANSI and ISO standards for data transmission on fiber optic lines in a local area network (LAN) that can extend in range up to 200 km (124 miles). The FDDI protocol is based on the token ring protocol. In addition to being large geographically, an FDDI local area network can support thousands of users. FDDI is frequently used on the backbone for a wide area network (WAN).
DEFINITION of hard disk
A hard disk is part of a unit, often called a “disk drive,” “hard drive,” or “hard disk drive,” that stores and provides relatively quick access to large amounts of data on an electromagnetically charged surface or set of surfaces. Today’s computers typically come with a hard disk that contains several billion bytes (gigabytes) of storage.
DEFINITION of operating system
What is an operating system? An operating system (sometimes abbreviated as “OS”) is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer.
DEFINITION of namespace
In general, a namespace uniquely identifies a set of names so that there is no ambiguity when objects having different origins but the same names are mixed together. Using the Extensible Markup Language (XML), an XML namespace is a collection of element type and attribute names. These element types and attribute names
