The 512 MB area following the internal RAM region, starting at address 0x40000000, is reserved for peripherals that are normally built into the microcontroller. The 1 GB area starting at address 0xA0000000 is instead used to map external memory chips and other devices that can be memory-mapped in the MCU addressing space, but are not part of the original chip package. In order to correctly access the peripherals, the configuration of the internal components within the MCU packaging and the addresses of the memory-mapped devices must be known in advance. Code execution is never allowed in these regions.