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Course contents

  • How to Use This Puzzle Bank
  • SystemVerilog Language Puzzles25
    • Datatype and Bit Puzzles
      • X-Bit Comparisons and Mixed Arithmetic
      • Signed vs Unsigned Comparison Trap
      • Type Cast Controls Sign Extension
      • Signed Part-Select Is Still Unsigned
      • X Collapse into 2-State `int`
      • Expression Width Drops the Carry
    • Fork Join Puzzles
    • Queue and Array Puzzles
    • String and Casting Puzzles
    • SystemVerilog Language Puzzles: Tricky Q&A
  • Difficulty Guide
  • Full Topic Map
  • Interview-Day Tips
  • Study Route: One Week Before the Interview
  • Study Route: Two Weeks
  • Study Route: Four Weeks (Full Course)4
  • OOP & Testbench Puzzles25
  • Concurrency & Timing Puzzles25
  • Randomization & Constraint Puzzles25
  • SVA Assertion Puzzles25
  • Functional Coverage Puzzles25
  • Logic & Aptitude Puzzles25
  • Scenario & Debug Puzzles25
  • UVM Testbench Puzzles25
  • Clock, Reset & CDC Puzzles25
  • Bus and Interface Protocol Puzzles25
  • Interview Prep: Puzzle Rounds7
  • DV Puzzle Cheatsheet
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←SystemVerilog Language Puzzles
  1. Topics
  2. DV Interview Puzzles
  3. SystemVerilog Language Puzzles
  4. Datatype and Bit Puzzles
On this page

    VLSI DV Interview PuzzlesAll levels

    Datatype and Bit Puzzles

    These puzzles target the places where SystemVerilog silently changes interpretation based on type: 4-state vs 2-state storage, signedness propagation, and operator-specific rules. Strong candidates can predict exact outputs by tracking width, sign, and unknown-bit semantics at every step.

    • 6topics
    • 6lessons

    Topics in this section

    1. 1X-Bit Comparisons and Mixed Arithmetic1 lesson
    2. 2Signed vs Unsigned Comparison Trap1 lesson
    3. 3Type Cast Controls Sign Extension1 lesson
    4. 4Signed Part-Select Is Still Unsigned1 lesson
    5. 5X Collapse into 2-State `int`1 lesson
    6. 6Expression Width Drops the Carry1 lesson

    About this puzzle set

    These puzzles target the places where SystemVerilog silently changes interpretation based on type: 4-state vs 2-state storage, signedness propagation, and operator-specific rules. Strong candidates can predict exact outputs by tracking width, sign, and unknown-bit semantics at every step.

    Puzzles in this topic

    Diagram
    1. X-Bit Comparisons and Mixed Arithmetic  [Medium]
    2. Signed vs Unsigned Comparison Trap  [Medium]
    3. Type Cast Controls Sign Extension  [Medium]
    4. Signed Part-Select Is Still Unsigned  [Medium]
    5. X Collapse into 2-State `int`  [Medium]
    6. Expression Width Drops the Carry  [Medium]

    Work each puzzle before reading the solution: predict the exact output or answer, name the rule that governs it, then check yourself.

    SV scheduling regions at puzzle scale

    Diagram
    SYSTEMVERILOG EVENT REGIONS (SIMPLIFIED ORDER)
    
    time slot T
       |
       +--> ACTIVE   : blocking statements, RHS sampling
       +--> INACTIVE : #0 queued work
       +--> NBA      : non-blocking LHS updates commit
       +--> OBSERVED : assertions sample stable design values
       +--> REACTIVE : testbench/program reaction code
    
    If behavior looks impossible, ask: "Which region saw which value?"

    Related topics

    • SystemVerilog Language Puzzles section

    • VLSI DV Interview Puzzles hub

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    See also

    • Fork Join Puzzles
    • Queue and Array Puzzles
    • String and Casting Puzzles