)The shape of a local-area network (LAN) or other communications system. Topologies are either physical or logical.
There are four principal topologies used in LANs.
bus topology: All devices are connected to a central cable, called the bus or backbone. Bus networks are relatively inexpensive and easy to install for small networks. Ethernet systemsuse a bus topology.
ring topology :All devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it. Ring topologies are relatively expensive and difficult to install, but they offer high bandwidth and can span large distances.
star topology: All devices are connected to a central hub. Star networks are relatively easy to install and manage, but bottlenecks can occur because all datamust pass through the hub.
tree topology: A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable.
These topologies can also be mixed. For example, a bus-star network consists of a high-bandwidth bus, called the backbone,which connects a collections of slower-bandwidth star segments.
For network diagrams, see Network Topology Diagrams in the Quick Referencesection of
- total zoom
Some digital camera manufactures advertise a camera’s zoom capability as a total zoom. When you see a total zoom listing, it is the digital zoom multiplied by the optical zoom. For instance, a camera touting a 20x total zoom could be a digital camera with 4x optical and 5x digital zoom.
- touch screen
A type of display screen that has a touch-sensitive transparent panel covering the screen. Instead of using a pointing device such as a mouse or light pen, you can use your finger to point directly to objects on the screen. Although touch screens provide a natural interface for computer novices, they are unsatisfactory for most […]
A small, touch-sensitive pad used as a pointing device on some portable computers. By moving a finger or other object along the pad, you can move the pointer on the display screen. And you click by tapping the pad.
A type of electronic display that senses physical touch by a person’s hands or fingers, or by a device such as a stylus, and then performs actions based on the location of the touch as well as the number of touches. A touchscreen display is useful for interacting directly with a computer or electronic device, […]
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)Refers to a computer in which the power supply, motherboard, and mass storage devices are stacked on top of each other in a cabinet. This is in contrast to desktop models, in which these components are housed in a more compact box. The main advantage of tower models is that there are fewer space constraints, […]