MICROPROCESSOR CIRCUIT FOR DATA CARRIERS AND A METHOD FOR ORGANISING ACCESS TO DATA STORED IN A MEMORY

摘要

The invention relates to a microprocessor circuit for organising access to data or programmes that have been stored in a memory. Said circuit comprises at least one microprocessor, a memory for an operating system and at least one memory for free programming using individual external programmes. The memory used for free programming has several memory areas containing corresponding address spaces, a qualifier being assigned to each address space. The microprocessor circuit also has means, which prior to the respective addressing of a memory area, load each qualifier assigned to a respective memory area into a first auxiliary register and load the qualifier of the addressed memory area into a second auxiliary register and which then compare the first and second auxiliary registers. At least one bit sequence containing access authorisations is also assigned to each address space of a memory area, which allows code commands and sensitive data to be protected from write access emanating from external programmes.