|
In 1969 IBM started marketing in five European countries the IBM 2750 Switching System – worldwide, the first stored-program-controlled PABX (Private Automatic Branch Exchange). Previously only electromechanical Strowger and Crossbar PABXs were available.〔''IBM 1750 Switching System – system overview'' IBM UK brochure GK10-6264-2 and IBM Germany brochure ''Vermittlungssystem IBM 1750 Systemüberblick'' GA12-12-2437-1〕 The 2750 was sold in France, Germany, Italy, and Belgium. The other systems were sold in these countries and the United Kingdom. The Netherlands installed some in IBM sites. The family of IBM 1750, 2750 and 3750 Switching Systems was developed from the IBM 1800 by the IBM La Gaude Research Laboratory near Nice, France for European markets only. Each system included twin stored-program controllers (each with 32K main storage, some 600,000 lines of code, and nightly and emergency automatic switchover), twin disks, and solid-state switching. Extension, trunk and tie lines were connected by discrete transistors on plug-in panels. The systems all had both voice and data functions – the marketplace largely bought them for their then-new voice and management functions. Early-1960s computers had hardly any typewriter-like terminals and no screens – the IBM Switching Systems introduced the novelty of simple digital-data capture from every touch-tone telephone extension. ==Extension facilities== Facilities for the extensions were revolutionary at the time and particularly valued by organisations in financial and other industries with relatively highly-paid office-based employees: * Touch-tone telephones (then practically new to Europe) for both voice and data entry * Call rerouting from multiple extensions to answer points * Camp on to a busy extension or external circuit with automatic call back * Short-code dialling to national and international numbers * Temporary call barring * Distinctive ring cadences (different cadences for internal and incoming external calls) * Dialled paging * Group answering * Authorised user intrusion * Add-on third party * Call pick-up * Non-dialled connection (an off-hook extension automatically dials an extension). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「IBM 1750, 2750 and 3750 Switching Systems」の詳細全文を読む スポンサード リンク
|