HDL/IP Conventions — Identify the Non-Altera Primitive Port Name Among common Intel (Altera) primitive/IP port identifiers, which of the following is <em>not</em> a standard Altera-style name?

Introduction / Context:
When instantiating vendor primitives or parameterized IP blocks in FPGA designs, using the correct port names is crucial for synthesis tools to bind signals properly. Intel (Altera) flows have recognizable conventions such as clk for clock and ena for enable. This question checks familiarity with naming that appears across megafunctions and primitive libraries.

Given Data / Assumptions:

• Typical Altera-style port names include clk, ena, aclr/sclr, aset/sset.
• Legacy TTL-style names like prn (preset) are common in 74xx datasheets, not in Altera IP naming.
• Context is HDL-based FPGA design, not discrete logic ICs.

Concept / Approach:
Map each option to vendor conventions. clk and ena are ubiquitous in Altera examples. While clr may sometimes appear, the canonical asynchronous clear is aclr and synchronous clear is sclr. The identifier prn for preset aligns with TTL flip-flops (e.g., 74LS devices) rather than Altera IP, making it the odd one out.

Step-by-Step Solution:
Recognize clk: standard clock input label in Altera IP.Recognize ena: standard enable input label.Consider clr: while aclr/sclr are preferred, clr is closer to the convention than TTL-style prn.Identify prn as a TTL-era preset label not typical for Altera primitives.

Verification / Alternative check:
Review Altera example instantiations (counters, RAMs, PLL wrappers). You will consistently find clk, ena, and clear/set ports with the a/s prefix; prn does not appear in these IP templates.

Why Other Options Are Wrong:

• clk: Correct and common.
• ena: Correct and common.
• clr: While not the most canonical, it aligns better with vendor style than prn.

Common Pitfalls:
Assuming TTL datasheet naming directly transfers to FPGA IP; vendors standardize their own HDL-friendly conventions to improve clarity and automation.

Final Answer:
prn