Mask ROM characteristics: Complete the statement—Information stored in a mask ROM is programmed during manufacturing and its contents are fixed thereafter. Which option best describes this behavior?

Introduction / Context:
Read-Only Memory (ROM) technologies vary by how data is placed into the device and whether it can be altered later. Mask ROM is the oldest and densest fixed ROM type: its bit patterns are defined during wafer fabrication using custom masks. Understanding mask ROM helps differentiate it from PROM, EPROM, and EEPROM in terms of flexibility and use cases.

Given Data / Assumptions:

• Technology: Mask ROM with patterns set in silicon at manufacture.
• No field programmability is available after fabrication.
• Nonvolatile behavior: data persists without power.

Concept / Approach:
Because data is encoded physically by diffusion/metal layers, mask ROM cannot be altered after production. This yields low cost per bit at high volumes but requires long lead times and firm data maturity. Devices such as PROM/EPROM/EEPROM provide post-fab programming or erasure methods and are chosen when data may change or volumes are lower.

Step-by-Step Solution:
1) Identify mask ROM: data defined by masks in the fab process.2) Recognize nonvolatile retention: no refresh or power required to keep data.3) Conclude that field modifications are impossible.4) Therefore, the accurate description is that the manufacturer stores the data and it cannot be changed.

Verification / Alternative check:
Device datasheets and manufacturing flows for mask ROM emphasize one-time definition and no reprogramming capability, unlike PROMs and E(E)PROMs.

Why Other Options Are Wrong:
“Can be modified” applies to field-programmable devices, not mask ROM. “Is lost if power is interrupted” confuses ROM with volatile RAM. Combining those two errors remains incorrect.

Common Pitfalls:
Equating any ROM with rewritable flash; assuming nonvolatile implies reprogrammable.

Final Answer:
is stored by the manufacturer and cannot be changed