Most parts of present computers are made with volatile devices such as transistors and dynamic random access memory (DRAM), which loses information when powered off. So computers are designed on the premise that power is “normally on.”
Back in 2000, the concept of “instant on” computers based on magnetoresistive random access memory (MRAM) emerged as a way to reduce that irritatingly long hang time associated with powering up – but it comes with a big tradeoff because it requires using volatile devices that continue to devour energy after the initial power up.
By 2001, researchers in Japan figured out a way to eliminate this pointless energy loss by using a nonvolatile function of advanced spin-transfer torque magnetoresistive random access memory (STT-MRAM) technology to create a new type of computer: a “normally off” one.
Read more at: Phys.org