Editing Packet Switch Stream (section)

=== PSS ===
A period of pre-operational testing with customers, mainly [[UK universities]] and [[computer manufacturer]]s, began in 1980. Packet Switch Stream launched as a commercial service on 20 August 1981 based on X.25/X.75. The experimental predecessor network (EPSS) formally closed down on 31 July 1981 after all the existing connections had been moved to PSS.

The network was initially based upon a dedicated modular packet switch using DCC's TP 4000 communication processor hardware. The operating system and the packet switching software were developed by [[Telenet]] (later on [[GTE]] Telenet). BT bought Telenet's system via [[Plessey Controls]] of Poole, Dorset who also sold Telex and traffic light systems. PSS was launched before Telenet's own upgrade of its network and, at the time, most other networks still used general purpose mini-computers as packet switches.

For a brief time the EEC operated a packet switched network, [[Packet switching#Euronet|Euronet]], and a related project [[Diane (project)|Diane]] to encourage more database and network services to develop in Europe. These connections moved over to PSS and other European networks as commercial X.25 services launched.

Later on the InterStream gateway between the [[Telex]] network and PSS was introduced based on a low speed PAD interface.

In addition, BT used Telematics packet switches for the Vascom network to support the [[Prestel]] service.

The network management systems were based in [[London]] and [[Manchester]]. Packet switches were installed at major trunk exchanges in most major conurbations in the UK. Network management was run on a system of 24 [[Prime Computer|Prime]] 63xx and 48xx computers running a modified versions of Revisions 20 and 22 of the [[PRIMOS|Primos]] operating system.

The [[DDN NIC|DNICs]] used by IPSS and PSS were 2341 and 2342 respectively.

The last PSS node in the UK was finally switched off Wednesday, 28 June 2006.