Verilog is the most Popular Hardware Description Language for a digital system. Any system like Microprocessor, memory network switch or Flip flop Can be described using this technology.
To clear an interview for the profile that requires Verilog, one must be thoroughly familiar with the concepts. The following set of questions will enable you to have good knowledge about it.
Top Verilog Interview Questions for 2026
1. What are Verilog parallel case and full case statements?
Parallel Case
It is a statement that matches only one case item. Otherwise, it becomes overlapping case items.
Full Case
It is a statement where binary patterns case expressions match a case item or a default.
2. Differentiate between == and ===.
== |
=== |
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Output can be 1,0 or X |
Output can be 0 or 1 |
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It can compare 1s and 0s but not Xs |
Can also compare Xs |
3. Differentiate between Verilog and VHDL
Verilog |
VDHL |
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It is an HDL used for digital systems |
It is an HDL used for electronic design automation |
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It is based on the “C” language |
It is based on Ada and Pascal languages |
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It is case sensitive |
It is not case sensitive |
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It is simple and easy |
It is complex |
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It is compact |
It requires more code lines |
4. What does wire refer to?
It is a physical connection between structural elements that enable Verilog to function. A continuous assignment or gate output denotes its value. A wire cannot store value when there is no connection between a and b. The Default value of a wire is Z.
5. What is reg in Verilog?
The reg represents the abstract data storage element. It is also called a register type integer, real and real-time. Its value is assigned within an always or an initial statement. The default value of reg is X.
6. What are Blocking and non-blocking in Verilog?
The blocking assignment completes the entire statement before the control goes to the following statement. It behaves similarly to older programming languages. It is symbolized as =.
A non-blocking assignment evaluates the right-hand side for the current time unit and the left-hand side later at the end of the time unit. It is symbolized as
7. Differentiate between Task and Function.
Task |
Function |
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Enable a function and additional versions of a task. |
It cannot enable a task but can enable other functions. |
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Can contain any statements |
Can yield one value |
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Can use 0, input, or output statements |
Cannot use input or output statements |
8. What is the Sensitivity list?
It specifies the list of the signals one wants to cause the code during the process to be evaluated when it changes its state.
9. Explain $monitor, $display and $strobe.
- These commands have similar syntax and show text on the screen during simulation.
- $display and $strobe appear once when executed.
- $monitor appears every time a parameter is changed.
10. What is transport delay?
This delay is caused by the wires connected with gates. The signal is due to the wire’s resistance and inductance.
11. What is the inertial delay?
The delay caused by the output change happens in the gate.
12. What are the ways of writing FSM code?
- All input decoders, output decoders, and present states are combined in one process.
- Where sequential and combinational circuits are separated in different processes.
- Where input decoder and present state are combined, but output decoders are separated.
- Where all three inputs are separated into three processes.
13. Explain deposit and force command
Deposit
This command is used to give an initial value to a signal. But it will hold it until it is overwritten. For example, depositing 1 to a flip-flop will remain the same until simulation changes it to a new value.
Force
It is used to drive signals at any time stamp of the simulation.
14. Explain freeze and drive
Freeze
It is used to put a value on a signal. Value remains the same throughout the simulation.
Drive
It puts value on a signal but changes to a new value when updated by a simulation.
15. What does timescale 1 Ns/1 Ps mean?
It means all delays are interpreted in nanoseconds, and fractions are rounded off to the nearest picosecond.
16. Between variable and signal, which will be updated first?
The signal will be updated first.
17. What are the features of VHDL?
Very High-speed integrated circuit HDL describes and simulates the system before making it into a digital one. Its features are
- Complexity management
- Design data portability
- Independent of technology
- Efficient and less time consuming
- Readability
18. What is PLI?
It is the Programming Language Interface used for enabling C programming in Verilog. It performs multiple tasks
- Passing data
- Altering and returning object value in the design hierarchy
- Accessing simulator database
- Monitoring alterations in the design hierarchy
19. What is a continuous assignment?
When inputs of the right-hand side drive the left-hand side, it is a continuous assignment. It also means that changing the right side will change the whole equation. The target is wire driven by right-hand side inputs. It is used to synthesize combination logic.
20. Explain the repeat loop.
It is similar to the loops of a common programming language. It repeats a code for the number of times mentioned within the code. It reduces the redundancy in code lines.
Syntax
Repeat(
21. What is Virtual and Pure virtual function in Verilog?
Virtual |
Pure virtual |
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It allows the overriding of a function in a derived class |
It has only declaration and no implementation |
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The base class doesn’t need to implement a virtual function |
Any derivative class must implement the function |
22. What are Semaphores?
It controls access to shared resources. It is used for mutual exclusion, primary synchronization, and accessing control of shared resources. It can be viewed as a bucket with several keys during its creation. The Execution process requires one of the keys.
23. What is the Factory and Factory pattern?
A factory creates different objects for a prototype. It is done By calling the corresponding constructor when different classes are registered with the factory.
The Factory pattern directly creates an object without calling the constructor method. It allows the use of polymorphism for object creation.
24. What is Callback?
A callback is when a function calls another function taking the first one as an argument. It is used when an event happens. It includes calling back a function
- to inject errors on transactions
- To train depending on transactions
- In the event of a specific occurrence
25. What is DPI called?
The Direct programming interface is a bridge between system Verilog and any other foreign programming language like Python. It ensures direct inter-language function calls doing languages on both sides of the interface. It supports both functions and tasks across the boundary.
26. What is Parameter and Typedef in Verilog?
A parameter is a constant value within the module structure used to define various attributes for the module. It also characterizes the behavior and physical representation of the module.
Typedef Enables users to craft unique names for type definitions for frequent use in their codes. They are easily used while building technical array definitions.
27. Explain some uses of Clocking Blocks
Clocking Block is used for
- Specifying synchronization characteristics of a design
- Testbench driving the signals at the right time
- Cleaning the drive and sample design and race-free operations in specific applications
28. What is the need for an Alias in Verilog?
An alias statement offers a bidirectional and short circuit connection. Usually, a Verilog has a one-way assign statement which may have delay and strength changes for unidirectional assignment.
