Microcircuit for a chip card comprising a protected programmable memory

Abstract

A microcircuit for a multi-application chip card, comprising notably a read-only memory (12), a programmable memory (13), and an addressing control circuit (14) for the programmable memory. The programmable memory (13) is subdivided into at least a repertory region (ZR) and an application region (ZA), the repertory region (ZR) comprising, for each application loaded therein, at least a reference code of an application i present in the region ZA.sub.i as well as the addressed ZA.sub.il and ZA.sub.ih, respectively, of the beginning and the end of the region ZA.sub.i allocated to the relevant application. The microcircuit also comprises apparatus (25 to 50) for inhibiting any command (R, W or E) for the programmable memory (13) when it relates to an address outside the interval ZA.sub.il -ZA.sub.ih of the application being processed, except when it concerns a specific priority operation provided by a program permanently stored in the read-only memory (12).