SNIU028D February 2016 – September 2020 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
When the UCD3138 is reset or powered up, control goes first to the ROM bootstrap program. The ROM bootstrap initializes the device and then performs a checksum on the Program Flash. If the checksum matches, the ROM turns control over to the customer supplied program in the Program Flash.
If the checksum does not match, control stays in the ROM, and the flash can be reprogrammed.