HDL-based frequency counter design: identify which of the following is not a major functional block of a typical frequency counter (as implemented in hardware description languages such as VHDL/Verilog). Consider the standard blocks used: input conditioning, timing and control, counting/accumulation, and display/output handling.

Introduction / Context:
A digital frequency counter, whether built discretely or in HDL (VHDL/Verilog), follows a well-known architecture. The key blocks include input signal conditioning, a timing and control unit to define the sample window, a counter/accumulator to tally pulses, and a display path (register plus decoder) to present the result. This question checks recognition of an element that is not core to that architecture.

Given Data / Assumptions:

• We are discussing a generic frequency counter implementation.
• Essential blocks typically include: Schmitt trigger or comparator (conditioning), timing/control, counters, display register, and display decoder/driver.
• Bit-shifting is not inherently required to count edges within a timed window.

Concept / Approach:
The architecture counts input edges within a precisely known gate time (sample interval) and latches the result. Decoding and display logic then show a human-readable value (often BCD to 7-segment). A “bit shifter” is useful in serial I/O or arithmetic operations, but it is not an essential block for frequency counting.

Step-by-Step Solution:

Verification / Alternative check:
Block diagrams in textbooks consistently omit a shifter in basic frequency counters unless specific serial interfaces are added.

Why Other Options Are Wrong:

• Display register: needed to freeze the measured value while the next interval counts.
• Decoder/display: needed to drive 7-seg or similar modules.
• Timing and control: essential to define accurate gate time.

Common Pitfalls:
Confusing optional serial-output features (which could use shifters) with core counter architecture.

Final Answer:
Bit shifter