In Altera MAX-series CPLDs using the MAX+PLUS II tool, a macrocell can automatically “borrow” product terms from adjacent macrocells in the same LAB. How many product terms can be borrowed from each of the three adjacent macrocells?

Introduction / Context:
CPLDs implement sum-of-products logic using product terms. When a single output equation needs more product terms than a single macrocell natively provides, many CPLD families allow “product-term expansion,” borrowing terms from neighboring macrocells inside the same logic array block (LAB). This question probes your understanding of how many product terms can be borrowed per neighbor in MAX+PLUS II flows for MAX-series devices.

Given Data / Assumptions:

• Target: Altera (Intel) MAX family CPLD macrocells.
• Tool: MAX+PLUS II compiler.
• Mechanism: product-term borrowing (parallel expanders) from three adjacent macrocells in the same LAB.
• We must select the correct count per adjacent macrocell.

Concept / Approach:
Product-term expansion allows a macrocell's OR plane to accept additional product terms sourced from neighboring macrocells via internal expanders. MAX+PLUS II automates this borrowing during fitting, up to a defined limit per neighbor, thus enabling larger SOP equations without external device resources.

Step-by-Step Solution:
Recognize that each macrocell supports a base number of product terms.When more are needed, the fitter checks adjacent macrocells for available terms.The automatic limit enforced by the tool per neighbor in the same LAB is 5 product terms.Therefore, with three neighbors, up to 15 additional terms can be aggregated (subject to availability).

Verification / Alternative check:
Device handbooks and tool user guides describe “parallel expanders” that provide a fixed number of additional terms per adjacent macrocell. Historical training materials commonly cite 5 per neighbor for these devices.

Why Other Options Are Wrong:
4/6/7 do not match the standard per-neighbor borrowing limit documented for these flows; choosing them would over- or under-state the actual tool constraint.

Common Pitfalls:
Confusing total borrowable terms with per-neighbor limits; assuming borrowing works across LAB boundaries (it does not—limited to the same LAB).

Final Answer:
5