PISO (parallel-in/serial-out) shift register behavior: Evaluate the statement: “A parallel-in/serial-out shift register loads all data bits simultaneously and then shifts them out one bit per clock.”

Introduction / Context:
Shift registers are fundamental serial/parallel converters used in digital systems for data serialization, buffering, and communication. A PISO (parallel-in/serial-out) variant is common when multiple data lines must be captured at once and transmitted over a single wire to save pins or bandwidth.

Given Data / Assumptions:

• Device type: PISO shift register.
• Control: a load signal to capture parallel data, then clock pulses to shift out serially.
• No special features (e.g., tri-state serial outputs) are needed to define core behavior.

Concept / Approach:
In a PISO, asserting LOAD captures the N-bit parallel word into internal flip-flops simultaneously. Subsequent clock pulses shift data toward the serial output, emitting one bit per clock (MSB-first or LSB-first per design). This is the canonical operation and aligns with timing diagrams in datasheets for common devices.

Step-by-Step Solution:

Verification / Alternative check:
Laboratory test with a known pattern (e.g., 10110010): after parallel capture, observe the serial line emitting bits in sequence with each clock tick until all bits are transmitted.

Why Other Options Are Wrong:

• Incorrect: Conflicts with the definition of PISO.
• Only true for ring counters: Ring counters are not PISO shift registers.
• Only true with asynchronous load: Many PISO devices provide synchronous or asynchronous load; the parallel capture principle remains.
• Depends on tri-state outputs: Tri-state affects bus sharing, not core PISO behavior.

Common Pitfalls:
Confusing PISO with SIPO (serial-in/parallel-out); misreading bit order; forgetting to latch inputs before shifting begins, which can corrupt the output stream.

Final Answer:
Correct