Introduction / Context:
MOS technologies include PMOS, NMOS (single-channel processes), and CMOS (complementary MOS). Historically, early microprocessors and small memories used NMOS; PMOS was used even earlier. Modern mainstream digital ICs overwhelmingly use CMOS due to power and density advantages.
Given Data / Assumptions:
- Legacy designs (1970s–early 1980s) often used NMOS for microprocessors and memories.
- CMOS supplanted NMOS/PMOS because it offers low static power and high integration.
- The statement is assessed in a general, current-technology context.
Concept / Approach:
“Commonly used” should reflect current industry practice. Today, small memories (SRAM, ROM, Flash) and microcontrollers/processors are fabricated in CMOS logic processes (or mixed-signal CMOS variants). PMOS-only or NMOS-only processes are not the common choice for mainstream products.
Step-by-Step Solution:
Identify historical vs. modern → NMOS/PMOS were common historically; modern practice is CMOS.Assess the phrase “commonly used” → in modern practice, false for PMOS/NMOS-only processes.Therefore, the statement is incorrect in contemporary context.
Verification / Alternative check:
Review any current foundry PDK catalog; mainstream digital offerings are CMOS-based nodes.
Why Other Options Are Wrong:
Correct: Would misstate current industry norms.Correct only for legacy 1970s designs: While historically true, the prompt asks about general/common usage today, hence overall incorrect.Correct only below 1 kb density: Technology preference is not dictated solely by tiny memory size; CMOS still dominates.
Common Pitfalls:
Assuming a historically accurate statement remains true today.Confusing device-level PMOS/NMOS transistors with single-channel process technologies.
Final Answer:
Incorrect
Discussion & Comments