Comparator expansion inputs — purpose and target width In a standard 4-bit magnitude comparator (such as the 7485), the expansion (cascading) inputs are provided to allow easy expansion to what wider system size?

Introduction / Context:
Magnitude comparators include cascade or expansion inputs that let multiple devices be chained to compare wider words. Understanding the purpose of these pins helps designers scale from 4-bit building blocks to larger bit widths without redesigning the internal comparison logic.

Given Data / Assumptions:

• A single IC compares 4 bits (A3..A0 vs B3..B0).
• Expansion inputs accept results from a more significant comparator stage.
• Outputs from a less significant stage feed into a more significant stage when cascading multiple devices.

Concept / Approach:
To compare two n-bit numbers larger than 4 bits, chain devices so the most significant stage decides the overall relation unless equality holds there, in which case the next stage decides, and so on. The simplest and most common cascade is two 4-bit comparators forming an 8-bit comparator.

Step-by-Step Solution:

Verification / Alternative check:
Datasheets typically show example circuits where two 7485 devices are cascaded to achieve 8-bit comparison; more devices can be chained for 12 or 16 bits, but the canonical next step from 4 bits is an 8-bit system using two ICs.

Why Other Options Are Wrong:

• 4-bit: no expansion.
• BCD system and counter system: unrelated to comparator width expansion.
• 12-bit “without additional logic”: possible with three devices, but the immediate and most direct expansion target is 8 bits.

Common Pitfalls:

• Wiring expansion pins incorrectly (IA=B must be driven by the lower stage).
• Forgetting proper priority from MSB stage downward.

Final Answer:
8-bit system