One of the key features of Concerto™ is the memory protection unit which improves system reliability by defining the memory attributes; no access, read/write, or read only for different memory regions. If a program accesses a memory location that is prohibited by the MPU the processor generates a memory management fault, causing a fault exception and possibly causing termination of the process in the OS environment. The MMU provides up to eight different regions and an optional, pre-defined background region from 32-bits to 4 GB range. The Cortex™-M3 MPU memory map is unified, meaning that instruction accesses and data accesses have the same region settings. The MPU registers can only be accessed from privilege mode. The benefits of this is that it enforces the privilege rules, it separates processes, and it also enforces the access rules when reading and writing to the memory.