Communications processor system with control of downloaded tasks

摘要

A communications processor system 10b that permits communications task code to be safely downloaded from a host system. Direct access to local memory 15b of the communications processor system 10b is permitted only during a downloading process while system 10b in a reset state. This downloading process is implemented with a special control register. In user mode, the system 10b controls access to local memory 15b by downloaded task code. Specifically, access is prohibited with respect to privileged memory areas, and is limited to a relatively small predetermined range of addresses with respect to other memory areas. This memory protection process is implemented with a special status register and a number of mapping registers.