T200 telex and data switching system
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The T200 by Hasler Ltd, Berne was the world's first stored-program-controlled line-switching system with digital transmission at bus-level. The first technical description for a stored-program-controlled telex exchange was produced in 1966, and led to an order from Cable and Wireless (Hong Kong) in December 1967, and subsequently to a number of switching systems in fifteen countries around the world developed from the original T200 system and all based on the principle of majority processing, using three processors running synchronously and redundantly.
The first T201 system entered service in Hong Kong in 1972, and the last T203 system was switched off on Lugano, Switzerland, in 2020 and stored in the Swiss Museum of Communication in Berne.
Initial development
The first T201 exchange was based on solid state technology (TTL) and used duplicated Ampex core memories for central storage. It entered service in Hong Kong in 1972. At the same time, a project was being formulated in Switzerland for an Integrated Telecommunications Network (Integriertes Fernmelde-System CH): Decision to base the project on the T200-System