SNIU028D February 2016 – September 2020 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
The memory map changes primarily because the vectors – for reset, interrupts, and faults – are located starting at location 0 in memory. When the UCD3138 powers up, the ROM needs to control the vectors. When the memory is configured, but the ROM is still executing, the ROM still needs to control the vectors.
Then when control is handed over to the customer program in FLASH, the vectors need to be assigned by the customer for most efficient execution.