Difficulty: Easy
Correct Answer: PAL
Explanation:
Introduction / Context:
Programmable logic devices come in many architectural flavors. Two historically important types are PALs and GALs. PALs generally provide a programmable AND plane and a fixed OR plane, while GALs add reprogrammable technology and versatile output macrocells. Understanding the architectural hallmark of a PAL helps you recognize its capabilities and limitations.
Given Data / Assumptions:
Concept / Approach:
The defining characteristic of a PAL (Programmable Array Logic) device is exactly this sum-of-products organization with a programmable AND matrix and fixed OR summation. Many PALs were OTP, distinguishing them from later GALs that used erasable technologies (e.g., EEPROM) and offered per-pin OLMC flexibility.
Step-by-Step Solution:
Verification / Alternative check:
Historical datasheets and textbooks present classic PAL block diagrams showing an AND matrix with fixed OR gates driving outputs, sometimes with simple output enable/inversion controls.
Why Other Options Are Wrong:
GAL: similar purpose but reprogrammable with more flexible OLMCs.
CPLD: multi-macrocell blocks with wider interconnect; not necessarily fixed OR planes as in classic PALs.
SPLD: a generic category that includes PAL and GAL; not specific enough to match the exact description.
Common Pitfalls:
Confusing the general SPLD category with a specific architecture. Here the exact structure and OTP cue point to PAL.
Final Answer:
PAL
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