A point of sale terminal is disclosed that provides all of the usual point of sale terminal functions, but that is entirely field portable. Data pertinent to each purchase can be input to the terminal via a keyboard assembly, a touch-screen display or a signature-capture screen assembly, or via an antenna...http://www.google.com.au/patents/US5408078?utm_source=gb-gplus-sharePatent US5408078 - Portable point of sale terminal
