The Memory Protection Unit is embedded on the SAM3U. It supports up to eight regions that can be configured from 32 bytes to 4 Gigabytes. There are different protection rules that are based on the type of transaction, so the different regions can be configured with different access levels. An MPU violation will cause an exception to occur, this is the Memory Management Fault exception. There are several situations when it is useful to apply the MPU: to protect data from untrusted user programs, to make memory regions read-only, and to isolate memory regions in a multi-tasking system.