______ can be erased by ultraviolet light.

Question

Examoogle · Accepted Answer

EPROM

Explanation: EPROM (Erasable Programmable Read-Only Memory) is a type of non-volatile memory that retains its data when the power supply is turned off. It is designed to be erased by exposure to high-intensity ultraviolet (UV) light through a transparent quartz window located on the chip package.

Working Principle: The EPROM utilizes a FAMOS (Floating gate Avalanche injection Metal Oxide Semiconductor) transistor. Data is stored by trapping electrons on an isolated floating gate; when exposed to UV light, the photon energy is sufficient to excite the electrons, allowing them to escape the floating gate and revert the memory cell to its original unprogrammed state.

Key Formulas: $E = h
u = \frac{hc}{\lambda}$ — Energy of UV photons required to overcome the potential barrier of the floating gate

Key Points: EPROM is non-volatile; data persists without power.; Erasure requires removing the chip from the circuit and placing it under a UV lamp for 15-20 minutes.; The chip must have a quartz window for UV light penetration.; Programming EPROM is done via electric charge injection.

Advantages: Reusable memory compared to PROM; Non-volatile storage; Cost-effective for development and prototyping

Disadvantages: Cannot be erased electrically in-circuit; Entire chip must be erased at once; Slow erasure process compared to Flash or EEPROM

Applications: Microcontroller program storage; Embedded system firmware development; Legacy digital circuits

Additional Info: Masked ROM is programmed during fabrication and cannot be altered.. PROM (Programmable ROM) can be programmed once using a high-voltage pulse but cannot be erased.. EEPROM (Electrically Erasable PROM) allows individual byte erasure using electrical signals.

Answer: D is correct — EPROM (Erasable Programmable Read-Only Memory) uses a quartz window for UV light exposure to erase stored data.

Exam Tip: Always remember that 'Erasable' in EPROM usually implies UV erasure, while EEPROM specifically denotes 'Electrical' erasure, which is significantly more convenient for modern systems.

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