Centrally controlled telephone exchange - has extra memory banks used for semi-permanent signals read cyclically in normal operation

摘要

The control centre of a communications facility esp telephone exchange has two memory banks. The first is for short term operations eg making connections. The second is for both permanent information eg the mode of operation of the exchange, and semi-permanent information eg authentication codes, special services. Three further stores are envisaged, chiefly to provide a permanent record in case of electricity supply failure, but also to assist in the storage of and introduction of changes to, semi-permanent information. This enables rapid recovery after breakdown and assists in normal operations.