Non-volatile memory
Non-volatile memory typically refers to storage in semiconductor memory chips , which store data in floating-gate memory cells consisting of floating-gate MOSFETs ( metal–oxide–semiconductor field-effect transistors ) , including flash memory storage such as NAND flash and solid-state drives ( SSD ) , and ROM chips such as EPROM ( erasable programmable ROM ) and EEPROM ( electrically erasable programmable ROM ) . 
<triplet> semiconductor memory <subj> chips <obj> subclass of <triplet> solid-state drives <subj> flash memory storage <obj> has part <subj> NAND flash <obj> has part <triplet> EPROM <subj> programmable ROM <obj> subclass of