<Tr> <Th> Early stage NVRAM </Th> </Tr> <Tr> <Td> <Ul> <Li> FeRAM </Li> <Li> MRAM </Li> <Li> PCM </Li> </Ul> </Td> </Tr> <Ul> <Li> FeRAM </Li> <Li> MRAM </Li> <Li> PCM </Li> </Ul> <Tr> <Th> Magnetical </Th> </Tr>

The type of memory that must have a constant power supply is