Read-only memory (ROM) – which statement best describes its user alterability and retention characteristics?

Introduction / Context:
Read-only memory (ROM) refers to memory whose contents are fixed for normal operation. The data is established at manufacture (mask ROM) or by a one-time programming step (PROM) and is not changed by the system or user during routine use. Understanding ROM clarifies how firmware and lookup tables are delivered in embedded systems.

Given Data / Assumptions:

• “User” means the system integrator or end user during normal use.
• ROM contrasts with RAM (read/write) and with EEPROM/Flash (rewritable nonvolatile).
• We discuss functional behavior, not interface timing details.

Concept / Approach:
The defining property of ROM is immutability from the user’s perspective. While various ROM technologies exist, they share that the stored pattern is fixed during normal device operation. ROM is also nonvolatile, retaining data without power. Therefore, the statement that a ROM’s data can never be altered by the user precisely captures the category.

Step-by-Step Solution:

Verification / Alternative check:
Datasheets for mask ROM/PROM specify read operations only and lack erase/write commands, confirming user immutability.

Why Other Options Are Wrong:
Unlimited capacity is untrue; refresh is a DRAM property; “maintains storage as long as power is applied” describes volatile RAM, not ROM; auto-erase on power-up is not a ROM behavior.

Common Pitfalls:
Confusing ROM with EPROM/EEPROM/Flash, which are erasable but not categorized as ROM in everyday usage when rewrite is possible.

Final Answer:
whose data can never be altered by the user