Introduction / Context:
Hardware description languages differ in syntax and sectioning. VHDL uses entities and architectures with declarative regions, while Altera’s AHDL uses a SUBDESIGN/VARIABLE style. Confusing these can cause errors in tool flows and assessments.
Given Data / Assumptions:
- Statement mentions VHDL and a “VARIABLE section” positioned between “SUBDESIGN” and logic.
- VHDL entities/architectures do not include “SUBDESIGN.”
- VHDL distinguishes signal vs. variable usage and scope.
Concept / Approach:
In VHDL, signals are declared in an architecture’s declarative region; variables are declared inside processes, procedures, or functions (or in protected types), not in a global “VARIABLE section” between named blocks called SUBDESIGN. The term SUBDESIGN and a dedicated VARIABLE section belong to AHDL, not VHDL.
Step-by-Step Solution:
Identify language markers: “SUBDESIGN/VARIABLE” → AHDL, not VHDL.Recall VHDL structure: entity (ports) + architecture (signals, components, constants).Variables in VHDL appear inside processes; signals appear in the architecture declarative part.Therefore, the claim about VHDL is inaccurate.
Verification / Alternative check:
Check any VHDL template: no SUBDESIGN section exists; signal declarations precede the begin keyword in the architecture.
Why Other Options Are Wrong:
Correct / True for both: Contradicted by VHDL syntax.Only true for SystemVerilog: SystemVerilog uses modules/interfaces; no SUBDESIGN/VARIABLE section.
Common Pitfalls:
Mixing vendor-specific AHDL examples with standard VHDL code.Treating variables and signals as interchangeable; they differ in assignment timing and scope.
Final Answer:
Incorrect
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