Monroe's 'Full Automatic' calculating machine, 1922.

Telephone exchange at Paddington station, 22 July 1942.

Internet switch, 1996.

Internet switch, 1996.

Internet switch, 1996.

Mobile cellular telephone, 'Star T-A-C', by Motorola, c.1990's.

Mobile cellular telephone, 'Star T-A-C', by Motorola, c.1990's.

Tivoli steps and graffiti, Lisbon, Portugal, 2005.

Telephone exchange operators in gas masks, 31 October 1938.

'Take 3 Easy Steps to Paris from £16', BR(CPU) poster, 1980.

Poulsen's Telegraphone, 1903.

Poulsen's Telegraphone, 1903.