What Is EPROM? How Many Times Can It Be Erased?

General
1

Hey everyone,

I’ve been reading up on different types of memory, and I came across something called EPROM. Can anyone explain what exactly EPROM is and how EPROM works? I know it’s an older technology, but I’m curious about how it differs from other memory types like EEPROM or flash memory. Also, what were its main uses back in the day?

Thanks!

2

Hello, EPROM, or Erasable Programmable Read-Only Memory, is a type of memory chip that stores data permanently but can be erased and reprogrammed if needed.

Unlike regular RAM, which loses all data when the power is turned off, EPROM retains information even when the system is powered down. This made it very useful in early computers, embedded systems, and other devices where permanent data storage was essential.

The term “programmable” refers to the fact that users could write data to it after it was manufactured, and “erasable” means that they could erase and rewrite that data if needed.

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There are two primary types of EPROM: UV EPROM and EEPROM.

UV EPROM (the classic version) requires exposure to ultraviolet (UV) light to erase its data. These chips often have a little window on top to allow the UV light to penetrate and erase the stored information. Once erased, the chip can be reprogrammed with new data.

EEPROM (Electrically Erasable Programmable Read-Only Memory), on the other hand, allows users to erase and reprogram the data electrically, without the need for UV light. This makes EEPROM more convenient and is one reason it eventually became more popular.

An EPROM chip can generally be erased and reprogrammed around 1000 times before it starts to degrade and become unreliable. This was a decent number of cycles for its time, but it pales in comparison to modern memory technologies like flash memory.

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While both EPROM and EEPROM are types of memory that can be erased and rewritten, the key difference lies in how they are erased:

  • EPROM requires a UV light source to erase its contents. This process is not immediate; it can take several minutes to complete.
  • EEPROM, on the other hand, can be erased electrically, making the process faster and more convenient.

Additionally, EEPROM allows for selective erasing of data, meaning you can erase individual sections of memory without affecting the entire chip.

You can see a detailed table to compare them in this post: What Is Programmable ROM?

5

Thank you all. :blush: Have a good day.