Essential Information & explanations, latest texts & monographs on
Crossbar_switch.
Flip the Switch: Discover the Weight-Loss Solution and the Secret to Getting Started by Jim Karas
Cisco Field Manual: Catalyst Switch Configuration by David Hucaby
Flip the Switch : Lose the Excuses, Lose the Weight, and Get the Body You've Always Wanted by JIM KARAS
Interconnections: Bridges, Routers, Switches, and Internetworking Protocols (2nd Edition) by Radia Perlman
The Switch by Elmore Leonard
The Switch Book: The Complete Guide to LAN Switching Technology by Rich Seifert
Bait and Switch: Human Rights and U.S. Foreign Policy (Global Horizons) by Julie A. Mertus
Eating In The Light: Making the Switch to Vegetarianism on Your Spiritual Path by Doreen Virtue
CCNA Router and Switch eSIM by Inc. Cisco Systems
Perfect Switch by Lisa Plumley
The Switch by Lynsay Sands
Switch On, Switch Off by Melvin Berger
Cisco Switching Black Book: A Practical In-Depth Guide to Configuring, Operating and Managing Cisco LAN Switches by Sean Odom
The Switch by Sandra Brown
Practical Switching Power Supply Design by Martin Brown
Crossbar switch
A crossbar switch is an electromechanical device for switching telephone calls. They were first widely installed in the 1950s in both the United States and England, and from there quickly spread to the rest of the world. They replaced most earlier designs like the Strowger switch in larger installations.
Crossbar switches use switching matrices made from a two dimensional array of contacts arranged in an x-y format. These switching matrices are operated by a series of bars arranged over the contacts. These bars can be rocked from side to side by electromagnets. A second set of bars is set at right angles to the first (hence the name, "crossbar") and also operated by electromagnets. One set of bars carries spring loaded wire fingers that operate the contacts beneath the bars. By operating the electromagnets that move the bars, it is possible to close the contacts beneath the point where two bars cross. This then makes the connection through the switch to connect the telephone call.
Although the crossbar was technically more advanced that the earlier systems it replaced, it was mechanically much simpler. The design criterion was to have two hours of "downtime" for service every forty years, which was a huge improvement. The crossbar was also smaller for any given number of lines, which is why it was primarily used in high-use areas in larger cities. For this reason they were also typically the first switches to be replaced with digital systems, which were even smaller and more reliable. There are probably no working crossbar exchanges left, except in museums like the Science Museum in London.
The above article is adapted from from Wikipedia All Wikipedia article text is available under the terms of the GNU Free Documentation License
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