Memory technologies: which device is ultraviolet-light erasable and electrically programmable, allowing repeated erase-and-reprogram cycles during development?

Introduction / Context:
Developers historically used ultraviolet-erasable, electrically programmable memories to prototype firmware. By exposing the device window to UV light, stored charges are removed, enabling the chip to be reprogrammed many times before production.

Given Data / Assumptions:

• We are comparing ROM, PROM, EPROM, and RAM.
• Key features: erasability and programmability mechanism.
• Use case: iterative program development and testing.

Concept / Approach:
EPROM (Erasable Programmable Read-Only Memory) is programmed electrically but erased using ultraviolet light through a quartz window. PROM can be programmed once only (fuses blown). ROM is factory-programmed and not field-alterable. RAM is volatile and not used for permanent firmware storage.

Step-by-Step Solution:

Verification / Alternative check:
Device markings (e.g., 27xxx series) and quartz window packaging are characteristic of EPROMs, validating the answer.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing EPROM with EEPROM/Flash (which are electrically erasable; no UV required). The question explicitly mentions ultraviolet light.

Final Answer:
EPROM