ls. switch A device that establishes, monitors, and terminates a connection between devices connected to a network. Switched 56 Switched 56 is a legacy service that enables dialing and transmitting of digital information up to 56 Kbps in a manner similar to placing an analog telephone call. The service is billed like a voice line-a monthly charge plus a cost for each minute of usage. Any switched 56 offering can connect with any other offering, regardless of carrier. switching The process of establishing a connection between an input and an output. Switching occurs in many parts of a network, such as at a PBX, at the local exchange, at an IXC's office, or in X.25 or frame relay networks. It allows a subscriber to establish communication with multiple parties by sending an address to the switch which, in turn, attempts to make a connection. switching hub See Ethernet Switch symmetrical Techniques in which the decompression techniques are an exact reverse of the compression techniques. Used in Real-Time interactive video applications. synchpulse Oscillator circuits generate the horizontal and vertical sweep signals in a television receiver; they are controlled, in precise synchrony, by the movement of the scanning element at the camera. To achieve horizontal control, the camera sends synch pulses along with the luminance information. To control the vertical sweep oscillator, a synch pulse is sent at the end of each field. synchronization The process of controlling two or more systems SO that they establish a time-based relationship with each other. Clocks are used to ensure precision in the sending and receiving of bits or other signals; Glossary of Terms characters are spaced by time, not bits. system bus Analogous to the nervous system in the human body, the system bus serves to interconnect the microprocessor with memory, storage devices, and input/output hardware. Also known as DS-1 or T-carrier. High-speed digital transmission system characterized by a bit rate of 1.544 Mbps and subdivided, via time division m