Motorola developed a first-generation 256 kb magnetoresistive random-access memory (MRAM) based on a single magnetic tunnel junction and a single transistor that has a read/write cycle of under 50 nanoseconds.[17] Everspin has since developed a 4 Mb version.[18] Two second-generation MRAM techniques are in development: thermal-assisted switching (TAS)[19] and spin-transfer torque (STT).[20]