Users have direct access to the computers and devices attached to the network
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A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams. Show
Two very common types of networks include: You may also see references to a Metropolitan Area Networks (MAN), a Wireless LAN (WLAN), or a Wireless WAN (WWAN). A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a writing lab, school, or building. Computers connected to a network are broadly categorized as servers or workstations. Servers are generally not used by humans directly, but rather run continuously to provide "services" to the other computers (and their human users) on the network. Services provided can include printing and faxing, software hosting, file storage and sharing, messaging, data storage and retrieval, complete access control (security) for the network's resources, and many others. Workstations are called such because they typically do have a human user which interacts with the network through them. Workstations were traditionally considered a desktop, consisting of a computer, keyboard, display, and mouse, or a laptop, with with integrated keyboard, display, and touchpad. With the advent of the tablet computer, and the touch screen devices such as iPad and iPhone, our definition of workstation is quickly evolving to include those devices, because of their ability to interact with the network and utilize network services. Servers tend to be more powerful than workstations, although configurations are guided by needs. For example, a group of servers might be located in a secure area, away from humans, and only accessed through the network. In such cases, it would be common for the servers to operate without a dedicated display or keyboard. However, the size and speed of the server's processor(s), hard drive, and main memory might add dramatically to the cost of the system. On the other hand, a workstation might not need as much storage or working memory, but might require an expensive display to accommodate the needs of its user. Every computer on a network should be appropriately configured for its use. On a single LAN, computers and servers may be connected by cables or wirelessly. Wireless access to a wired network is made possible by wireless access points (WAPs). These WAP devices provide a bridge between computers and networks. A typical WAP might have the theoretical capacity to connect hundreds or even thousands of wireless users to a network, although practical capacity might be far less. Nearly always servers will be connected by cables to the network, because the cable connections remain the fastest. Workstations which are stationary (desktops) are also usually connected by a cable to the network, although the cost of wireless adapters has dropped to the point that, when installing workstations in an existing facility with inadequate wiring, it can be easier and less expensive to use wireless for a desktop. See the Topology, Cabling, and Hardware sections of this tutorial for more information on the configuration of a LAN. Wide Area Networks (WANs) connect networks in larger geographic areas, such as Florida, the United States, or the world. Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of global network. Using a WAN, schools in Florida can communicate with places like Tokyo in a matter of seconds, without paying enormous phone bills. Two users a half-world apart with workstations equipped with microphones and a webcams might teleconference in real time. A WAN is complicated. It uses multiplexers, bridges, and routers to connect local and metropolitan networks to global communications networks like the Internet. To users, however, a WAN will not appear to be much different than a LAN.
Direct Access Storage Device (DASD) Table of Contents
What Does Direct Access Storage Device (DASD) Mean?A direct-access storage device (DASD) is another name for secondary storage devices that store data in discrete locations with a unique address, such as hard disk drives, optical drives and most magnetic storage devices.It is a technology and term coined for storage devices that IBM developed for use with mainframe computers and some microcomputers. These developed into the modern hard disk and its variants like the optical disk, which today we would simply call secondary storage. Advertisement Techopedia Explains Direct Access Storage Device (DASD)Direct-access storage devices allow the host computer to access data directly from wherever it is stored within the storage device because each data chunk is saved in a discrete and separate location from other chunks, complete with a unique address. This allows the computer to directly point to that location to get the data. Access methods include indexed, sequential and direct (incorrectly referred as random access).Even if the exact location of the data is known, the speed of access is largely dependent on the capability of the storage device; for example, even if the exact data location within a tape drive is known, the only access method is sequential access because of the inherent design of the tape, which means it must go through all of the locations preceding the one that is needed. Additionally, the tape cannot run very fast. This is in contrast to a direct access disk, which can quickly spin the disk and move the read/write head to the correct track and sector in fractions of a second. Modern DASDs are internal and external hard disk drives that connect directly to the host computer via an IDE, SATA, eSATA, USB or FireWire interface. Unlike network-attached storage (NAS), DASDs become inaccessible once the device they are connected to goes offline. Related QuestionWhat is peer-to-peer content distribution? Advertisement Share this Term Related Terms
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TagsStorageTrending ArticlesPersonal Tech 7 Sneaky Ways Hackers Can Get Your Facebook PasswordArtificial Intelligence 7 Women Leaders in AI, Machine Learning and RoboticsWhat is direct access in computer?In computer storage, direct access is the process of reading and writing data on a storage device by going directly to where the data is physically located on the device rather than having to move sequentially from one physical location to the next to find the correct data.
What are direct access devices explain any one direct access device?A direct-access storage device (DASD) (pronounced /ˈdæzdiː/) is a secondary storage device in which "each physical record has a discrete location and a unique address". The term was coined by IBM to describe devices that allowed random access to data, the main examples being drum memory and hard disk drives.
Which of the following device is a direct access device?A direct-access storage device (DASD) is another name for secondary storage devices that store data in discrete locations with a unique address, such as hard disk drives, optical drives and most magnetic storage devices.
Which devices support direct access of data What does direct access mean ?)?Direct access storage devices (DASDs) are fixed or removable storage devices. Typically, these devices are rotating disk drives or solid state disks.
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