Random or urandom?

Understanding $random vs $urandom in SystemVerilog

This is an easy verification question that tests foundational knowledge of SystemVerilog's built-in randomization functions. It is commonly asked during interviews for design-verification and testbench-development roles to confirm that candidates understand the behavioural and practical differences between these two widely-used constructs.

The distinction between these functions affects how you seed testbenches, achieve reproducibility in simulation, and ensure proper randomness properties across test runs. Understanding when to use each one is essential for writing robust, maintainable testbenches and debugging non-deterministic failures.

• Seeding and reproducibility in simulation
• Distribution and randomness properties
• Use cases in constrained random verification