So I've had a lot of people come to me with problems with replacing their Dallas chips (or SRAM) with FRAM and it's always the same problem. They are using the regular FM1608s. The problem is a lot of hardware including Konami's Viper/Hornet hate the regular 1608s and they will always come up with an error which I'm guessing has to do with the speed, , so buy the FM1608B since they are faster.