EPROM erase granularity — is the key advantage of EPROM the ability to erase a single byte independently?

Electronics Semiconductor Memory Difficulty: Easy
Choose an option
  • A
    Incorrect — EPROM erases the whole device via UV exposure
  • B
    Correct — EPROM supports byte erase through its window
  • C
    Correct only on OTP-EPROMs (one-time programmable)
  • D
    Depends on the package (plastic vs ceramic)
  • E
    Correct for electrically erasable EPROM devices

Answer

Correct Answer: Incorrect — EPROM erases the whole device via UV exposure

Explanation

Introduction / Context:EPROM (Erasable Programmable Read-Only Memory) and EEPROM have similar-sounding names but very different erase mechanisms. EPROM devices are erased by ultraviolet (UV) light through a quartz window and the erase operation clears the entire chip at once. EEPROM and Flash enable electrical erase of bytes, words, or blocks.

Given Data / Assumptions:

  • The claim is that EPROM’s advantage is single-byte erase capability.
  • We consider standard UV-erasable EPROMs and OTP-EPROMs.
  • Erase granularity is the focus, not program granularity (programming is byte-oriented).

Concept / Approach:EPROM stores charge on floating gates. UV photons discharge all cells simultaneously when exposed for the specified time, returning the device to the erased (all 1s) state. No byte-level selective erase exists in EPROM. EEPROM (Electrically Erasable PROM) allows in-circuit, selective electrical erase—often at the byte or page level—without UV exposure, which is its key advantage for small updates.

Step-by-Step Solution:

Identify device type: EPROM vs EEPROM.Recap EPROM erase: bulk UV exposure through window.Recap EEPROM erase: electrical byte/page/block erase.Conclude the statement about EPROM single-byte erase is incorrect.

Verification / Alternative check:Look at EPROM datasheets (e.g., 27C256, 27C512): specify UV erase procedure and time; no byte erase command exists. EEPROM datasheets list byte/page erase/write commands.

Why Other Options Are Wrong:

“Correct via window”/“correct for electrically erasable EPROM”: confuses EPROM with EEPROM.“Only on OTP”/“depends on package”: OTP parts cannot be erased at all; package type does not change erase granularity.

Common Pitfalls:Mixing programming granularity (byte writes) with erase granularity; conflating EPROM and EEPROM terminology.

Final Answer:Incorrect — EPROM erases the whole device via UV exposure

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