What the difference between prom and eprom?

erasable prom

 

eprom holds what ever is stored even when the power is turned off, unlike RAM which can be written but will lose data when it looses power.

 

Then there's EEPROM (electrically erasable programable read only memory).

 

The bit patterns in a PROM are defined at the time of manufacture, in the mask.

The bit patterns cannot be changed or erased.

The bit patterns in an EPROM are defined by the user using an eprom programmer.

A UVEPROM (the one with the quartz lid on the top) is erased by exposure to short wavelength UV light.

The EEPROM is an electrically erasable EPROM, where you don't need the UV to erase data.

 

I never knew UVEPROM was real. I saw it in a si-fi thing where it was used as a fail safe on a AI. Do you know how it works, does it just erase it and set everything to 0 or 1 or is it destroyed in the process?

 

http://en.wikipedia.org/wiki/Programmable_logic_device" [Broken]