出典:Wikipedia
出典:『Wikipedia』 (2011/04/22 13:24 UTC 版)
The Rotary machine switching system was a type of automatic telephone exchange manufactured and used in Europe from the 1910s. It was developed by Bell Labs in the United States when they were developing the Panel system . The Rotary and Panel systems had many features in common, for example machine-driven switches and sequence switches (step switches) powered via shafts and clutches, and revertive impulsing from the switches back to the controlling Register which received the dial impulses; but the switches were smaller (200 rather than 500 outlets). The initial version was called 7A, succeeded by 7A1 and then 7A2; with a 7D rural system also.