On Tuesday, September 3, 2019, 03:18:40 AM PDT, \0xDynamite
   <dreamingforward@gmail.com> wrote:

   >The reason I asked because I can't figure out how you can get
   persistent memory without burning circuits.  An internal battery
   perhaps or a writable crystal, but.... how?
   In the early 1970's, the computer industry went from magnetic core
   ( [1]https://en.wikipedia.org/wiki/Magnetic-core_memory  ) to static
   and dynamic RAM, losing non-volatility in the process.   It was
   possible to run a CMOS static RAM on a tiny battery, to maintain data
   when the main system power was turned off.
    The industry developed UV-erasable EPROM as a substitute, which
   allowed only the erasure of the entire memory chip, , and some early
   EEPROM.  (Electrically erasable programmable Read-Only-Memory).
   Eventually "flash-EPROM" was developed.
   [2]https://en.wikipedia.org/wiki/Flash_memory
                           Jim Bell

References

   1. https://en.wikipedia.org/wiki/Magnetic-core_memory
   2. https://en.wikipedia.org/wiki/Flash_memory