Stored program control: Difference between revisions

Revision as of 00:06, 19 December 2019

Revision as of 16:42, 22 December 2019

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Second generation exchanges such as [[Strowger switch|Strowger]], [[Panel switch|panel]], rotary, and [[Crossbar switch|crossbar]] switches were constructed purely from electromechanical switching components with [[combinational logic]] control, and had no computer software control. The first generation were the manual switchboards operated by attendants and operators.

Later crossbar systems also used computer control of their switching matrices and may be considered SPC systems as well. Examples include the Ericsson ARE 11 (local) and ARE 13 (transit) as well as the North Electric NX-1E & D Switches and the ITT Metaconta 11, once found throughout Western Europe and in many countries around the world. SPC technology using analog switching matrices was largely phased out in the 1980s and had disappeared from most modern networks by the late 1990s,. ThereSome maysuch still be SPC Switchesswitches in some countries like Russia or Ukraine may still be in service.{{citation needed|date=December 2019}})

The addition of [[time-division multiplexing]] (TDM) decreased subsystem sizes and dramatically increased the capacity of the telephone network. By the 1980s, SPC technology dominated the telecommunications industry.