Perhaps a better way to say it is that an EPROM (Erasable Programmable Read-Only Memory) is a non-volatile storage device that does not require any type of standby power to maintain its contents.
EPROM and FLASH memory are actually fairly different in technology. A typical EPROM requires exposure to shortwave UV light to erase it, and it will only survive a relatively small number of erase/program cycles.
FLASH memory is much closer in function to an EEPROM (Electrically Erasable Programmable Read-Only Memory), with the key difference being that FLASH can be easily erased and rewritten without having to go through the electrical contortions that EEPROMs require. FLASH can also (usually) withstand a much higher number of write cycles before it starts to deteriorate.
RAM (Random Access Memory) is typically volatile, meaning that if the power goes away so does the memory's contents. The big advantage with RAM is that the access time for read and write is far faster than any EPROM or EEPROM.
Scary what I remember, sometimes...
Happy tweaking.
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Bruce "What was I saying?" Lane
Ruffler of feathers at inopportune moments