PAL internal structure — AND/OR array roles: Is the following statement correct? “A PAL consists of an array of fixed AND gates connected to a programmable OR array.”

Introduction / Context:
Programmable Array Logic (PAL) devices popularized fast, simple sum-of-products logic. Their internal structure determines how designers create product terms and sum them into outputs. Knowing which array is programmable is fundamental to understanding PAL equations and limitations.

Given Data / Assumptions:

• PALs implement sum-of-products: product terms (AND) feeding fixed-width OR gates.
• PAL AND array is programmable; OR array is typically fixed.
• Variants exist, but the classic PAL architecture follows this rule.

Concept / Approach:
Designers program the AND plane to select which input literals (true or complemented) define each product term. These terms feed fixed OR gates that combine a set number of products per output. By contrast, PLAs have both AND and OR arrays programmable. Therefore, saying “fixed AND and programmable OR” reverses the PAL’s canonical architecture and is incorrect.

Step-by-Step Solution:

Verification / Alternative check:
PAL datasheets and textbooks consistently illustrate a programmable AND matrix feeding fixed OR sums, sometimes followed by macrocells for output configuration.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing PAL with PLA; assuming both arrays are programmable in all SPLDs; overlooking macrocell behavior beyond the OR plane.

Final Answer:
Incorrect