And don't forget anti-fuse based one-time and few-time programmble memories.
Actually FRAM is only slightly younger than phase-chnage memmory and precedes MRAM and ReRAM by a considerable time.
Ramtron was founded in 1984 in Colorado Springs, Colorado and I was in the audience at the ISSCC at the unveiling of a prototype FRAM device in 1988.
Symetrix Corp. was founded in 1986 by Carlos Paz de Araujo, also in Colorado Springs.
So we could ask why has it taken so long to offer FRAM as an embeddede memory option?