MOS vs. TTL primary advantages Evaluate the statement: “The principal advantage of MOS ICs over TTL ICs is their fast operating speed.”

Introduction / Context:
MOS (and especially CMOS) technologies revolutionized digital ICs primarily by offering extremely low static power consumption and very high integration density, not by raw speed in their earliest incarnations. TTL traditionally offered shorter propagation delays than early MOS families, while consuming more power.

Given Data / Assumptions:

• Early MOS/CMOS: low power, high noise margins, high input impedance, wide supply ranges.
• TTL: faster in classic comparisons (e.g., LS/AS/F series) but with higher static power and fixed 5 V operation.
• Modern CMOS can be very fast due to process scaling, but the historical “principal advantage” remains low power and density.

Concept / Approach:
When teaching logic families, the “principal advantage” of MOS/CMOS is low power and ease of scaling integration density. Speed leadership historically belonged to ECL and, relative to early CMOS, to Schottky-TTL variants. Thus, claiming speed as the principal advantage of MOS over TTL is inaccurate.

Step-by-Step Solution:

Verification / Alternative check:
Review standard textbooks that present logic family tradeoffs; they consistently highlight MOS/CMOS low power and high density as the central benefits.

Why Other Options Are Wrong:
“Correct” misstates the classic comparison. The options invoking ECL-MOS hybrids or cryogenic operation are off-topic.

Common Pitfalls:
Confusing present-day high-performance CMOS (fast) with the general historical rationale for MOS adoption (power/density).

Final Answer:
Incorrect