Thank you everyone for contributing. I guess the picture is a bit clearer in my mind. So basically the OS is stored in flash memory or an SSD (SSD is composed of flash memory chips). I was looking at the Innuos web page for the Pulse Mini, and found this:
-Industrial-Grade SSD module specifically for the Operating System with power-loss protection
-Low-Density Parity Check ECC engine and Global Wear-Levelling technologies
I am assuming other manufacturers like Aurender, Lumin, etc. do the same.