Introduction:
Erasable Programmable Read-Only Memory (EPROM) is a classic non-volatile memory technology that can be erased using ultraviolet (UV) radiation through a quartz window in the package. This question validates awareness of EPROM erase mechanisms versus other non-volatile memories like EEPROM and flash.
Given Data / Assumptions:
- Device type: EPROM with quartz window (e.g., 27xx families).
- Erase mechanism: UV light exposure of sufficient energy and duration.
- Programming: high-voltage charge injection to a floating gate.
Concept / Approach:
EPROM stores bits by trapping charge on a floating gate inside a MOS transistor. UV photons with adequate energy discharge the trapped electrons via photoelectric effects, returning threshold voltages to their erased state. The process requires specific wavelength (commonly near 253.7 nm from mercury lamps) and exposure time (minutes) per datasheet recommendations.
Step-by-Step Solution:
Confirm technology: EPROM uses floating-gate MOS with a quartz window.Apply UV light for the recommended duration and distance.Verify erasure by reading the device; all bits return to the erased state (usually logic 1).
Verification / Alternative check:
Manufacturers specify erase times and wavelengths; device programmers include UV erasers designed for EPROMs.
Why Other Options Are Wrong:
Incorrect: Ignores the well-known UV erase property of EPROMs.Only true for EEPROM: EEPROM is electrically erasable, not UV-erasable.Only true below 300 nm wavelength: While germicidal 254 nm is standard, the key is sufficient photon energy per datasheet; it is not a strict single cutoff statement.
Common Pitfalls:
Confusing EPROM with OTP (one-time programmable) versions that lack a quartz window and cannot be UV-erased after final packaging.Assuming flashlight UV is adequate; intensity and exposure time matter.
Final Answer:
Correct
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