The idea goes back a long time. There used to be a product called Legato Prestoserve that used battery-backed SRAM. It was available in the early 1990s, maybe l

The idea goes back a long time. There used to be a product called Legato Prestoserve that used battery-backed SRAM. It was available in the early 1990s, maybe late 1980s. Here's some documentation about the version of it that Sun Microsystems licensed and sold: https://docs.oracle.com/cd/E19957-01/801-4896-11/Presto.chp1.html https://docs.oracle.com/cd/E19957-01/801-4896-11/Presto.chp1... It says: "Each NVSIMM contains memory, a battery, and power controller circuitry, which ensure that the memory is not lost when the system is shut-down or halts because of an abnormal condition." "Synchronous write requests to disk are intercepted, and the data is stored in non-volatile memory"