Plessey System 250

The Plessey System 250 was the first operational computer system to implement capability-based addressing, and the first sold commercially. It was designed as a real-time controller for computerized telephone switching systems. It had a multiprocessing architecture.

Manufactured by Plessey company plc in the United Kingdom in 1970, it was successfully deployed by the Ministry of Defence for the British Army Ptarmigan project and served in the first Gulf War as a tactical mobile communication network switch.