Fresh from their UKP5m System X contract from the London Stock Exchange earlier this week, Plessey and GEC have given details of the second generation digital public telephone exchange to be launched at Telecom 87 in Geneva in October. The new exchange, primarily for the export market is, as reported here in May (CI No 679), less than one-fifth the size of the current version, needs under a quarter the power, and, says GEC, represents a quantum leap in System X technology. An entire 25,000 Erlang trunk exchange now needs just 20 racks – under 50 square yards. The exchange features an enhanced digital switching subsystem – based on VLSI chips that connect 256 inputs to 256 outputs – capable of interconnecting 60,000 circuits. It has a new signalling processor subsystem, with 31 links on a single plug-in card, conforming to the latest CCITT standards and supporting new protocols including access to intelligent databases. ISDN connections can now be made at 144Kbps instead of only 80Kbps as before, and extra memory, up to 56Mb in groups of 8Mb, can now be plugged in. It has a design capability approaching 2m Busy Hour connections, although, so far, only 1m have been measured.
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