How to Erase EPROM

EPROM (Erasable Programmable Read Only Memory) chips have a ceramic body and a quartz window on top. The quartz window allows erasing of the data on the chip by using ultraviolet light exposure. When an EPROM chip is programmed, it contains different values, either 0s or 1s, on each floating-gate memory cell. If the gate is charged, it will have value of "0". If the gate is not charged, it will have a value of "1". When an EPROM chip is erased, all of the gates are uncharged, so the value will return to "1".

Things You'll Need

• EPROM eraser

Instructions

1. Remove all stickers, dirt and debris from the quartz window on top of the EPROM chip.

2. Plug the EPROM eraser into a wall outlet.

3. Open the EPROM eraser, or pull out the drawer that holds the chips. Place the EPROM chip into the eraser or chip drawer with the quartz window side facing the ultraviolet lamp.

4. Turn on the EPROM eraser, and set the timer to approximately 20 minutes.

5. Turn off the EPROM eraser, and remove the chip from the unit.

Tips & Warnings

• Check the manufacturer's recommendations for calibrating the light source on the EPROM eraser. Underexposed chips are not always fully erased.

• Never look at the ultraviolet light from the EPROM eraser while the unit is in operation. The light is capable of damaging eyesight.

• Do not leave the EPROM chips in the eraser for too long. Overexposure to ultraviolet light can damage the EPROM chip.

References

• The National Museum of American History's Chip Collection: ROM, EPROM and EEPROM Technology
• University of Akron: Computer Architecture
• The University of California at Berkeley: EECS 150 Lab #8 EPROMS