74164 Behavior — The SN74164 is a serial-in/parallel-out shift register with no synchronous parallel load feature. Evaluate the claim: “To synchronously load parallel data on the negative clock edge, set the parallel enable LOW.”

Introduction:
Not all shift registers support both serial shifting and parallel loading. The SN74164 device is a classic serial-in/parallel-out (SIPO) register: it shifts data in serially and presents the accumulated bits at parallel outputs; it does not provide a “parallel load” control that captures an entire word at once. This question asks you to judge a statement that incorrectly attributes a parallel-load capability to the 74164.

Given Data / Assumptions:

• Device: 74164 (or HC/HCT164 variants).
• Inputs: serial A/B (gated), clock, asynchronous clear.
• Outputs: parallel Q pins, updated by shifting.

Concept / Approach:
A true parallel load requires per-bit data inputs and a load control that selects those inputs at a clock edge. The 74164 exposes no per-bit data bus for parallel capture; it accepts serial data only. Therefore, any wording about “parallel enable LOW” for synchronous parallel loading is incompatible with the device’s feature set and is false.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

Common Pitfalls:

Final Answer: