Nonvolatile memories — UV-erasable category Which type of ROM device can be erased by exposure to ultraviolet (UV) light through a quartz window?

Introduction / Context:
Read-only memory (ROM) technologies differ in how (and whether) they can be programmed and erased. Recognizing how each type is altered in the field is essential for hardware maintenance, embedded updates, and legacy system repair.

Given Data / Assumptions:

• Mask ROM: contents fixed at manufacture; cannot be electrically or optically erased.
• EPROM: erasable programmable ROM with a quartz window; erased by UV light.
• EEPROM/Flash: electrically erasable, no UV window required.

Concept / Approach:
EPROMs use floating-gate transistors whose stored charge can be removed by high-energy UV photons. The chip package features a quartz window to allow UV light to reach the die. After erasure, the device can be reprogrammed with a PROM/EPROM programmer.

Step-by-Step Solution:
Identify which memories are field-erasable: EPROM, EEPROM/Flash.Determine which requires UV rather than electrical erase: EPROM.Therefore, the UV-erasable device is EPROM.

Verification / Alternative check:
EPROM packages (e.g., 27C256) have conspicuous windows labeled “Erase before programming” specifying UV wavelength and exposure times (often ~253.7 nm for several minutes).

Why Other Options Are Wrong:

• ROM/Mask ROM: Not erasable in the field.
• EEPROM: Erased electrically, not by UV.

Common Pitfalls:

• Confusing EPROM and EEPROM due to similar names; the extra “E” means electrical erase.
• Assuming all ROMs are nonerasable; modern nonvolatile memories include erasable variants.

Final Answer:
EPROM