EPROM (Erasable Programmable Read Only Memory) was a great invention that allowed hardware programmers to make changes to their code without buying new chips. The technology that preceded EPROM did not allow the data to be changed. That is the reason why it gained popularity pretty quickly among hardware makers and hobbyists. EPROMS allow them to fully deploy their program on the chip then test it, once bugs are found they can erase the EPROM then load a modified version for further testing.
Erasure of data is done by exposing the little window on its top side to ultraviolet light. UV light can even be found in sunlight, that’s why the EPROM window is usually covered to prevent accidental exposure to light sources. Although EPROM was a great advancement in technology, the erasure method still left some people wanting more. Exposing the window to light for a period of time meant that you would have to remove the chip and it would not be usable until the data is fully erased. There is also no possibility of having the data replaced by the end user.
These problems led to the development of a version of EPROM that is much easier to use. Which is named EEPROM or Electrically Erasable Programmable Memory. The only difference between the two is that you can erase an EEPROM with electricity. Although it might seem to be a very small difference, it resulted in major changes that turned the EEPROM into the new standard.
First and foremost, since the data can be erased with electricity, new programming boards were created that erased the content every time you want to enter new data. This simply meant that you would no longer wait in order to test the changes that you have made. EEPROM also lost the window since it doesn’t need that anymore, eliminating the risk of accidental erasure. EEPROM also allowed manufacturers to release patches if the program in the EEPROM had some faults. This reduced the amount of hardware that is being returned for replacement.
Sometimes, minor improvements can dramatically change the usability and reliability of the device. EEPROM is one of those that were very significant. The use of EPROM is now very rare since most people have switched to the much more convenient characteristics of EEPROM.