An apparatus for printing on a substrate includes a device for printing indicia on a substrate; a control that controls the indicia printing device, the control including apparatus for establishing a communicating link with an external device, the establishing apparatus including a protocol which utilizes...http://www.google.co.uk/patents/US5613007?utm_source=gb-gplus-sharePatent US5613007 - Portable thermal printing apparatus including a security device for detecting attempted unauthorized access
