Product-term expansion in PLDs — which feature borrows unused product terms from nearby macrocells? Identify the PLD feature name that increases the number of product terms available to a macrocell by borrowing unused terms from adjacent macrocells.

Introduction / Context:
In classic CPLD architectures (e.g., Altera MAX series), each macrocell has a limited number of product terms. Some designs require more product terms for a single output equation. Vendors provide “expander” mechanisms to borrow unused product terms from neighboring macrocells to meet this need.

Given Data / Assumptions:

• Macrocells reside inside a logic array block (LAB).
• Certain expanders make additional product terms available to a target macrocell.
• We must identify which named feature performs this borrowing in parallel.

Concept / Approach:
“Parallel expanders” add extra product terms to an equation by feeding additional ANDed terms directly into the OR stage of the target macrocell. This effectively widens the sum-of-products without moving the function to a different macrocell. “Shared expanders” generally distribute signals to multiple macrocells rather than increase a single macrocell’s product-term budget.

Step-by-Step Solution:

Verification / Alternative check:
MAX7000 family documentation describes both shared and parallel expanders, with “parallel” explicitly for borrowing product terms to expand an equation.

Why Other Options Are Wrong:

• Shared expander: aids sharing, not strictly increasing one macrocell’s term budget.
• Series/slice expanders: not standard names for the described function.

Common Pitfalls:
Assuming “shared” means “more terms”; in practice, it is about distributing existing terms, not expanding a single equation’s width.

Final Answer:
Parallel expander