According to a portable medium (IC card) of this invention, a memory area is divided into a system program area and a user program area. A text transmitted between the IC card and a host system connected thereto includes a command text and a response text. The command or response text includes a flag...http://www.google.co.uk/patents/US4827512?utm_source=gb-gplus-sharePatent US4827512 - Programmable portable electronic device
