Family resemblance: The GAL16V8 architecture is most similar to which earlier programmable logic device family?
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APAL
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BPROM
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CPLD (generic category)
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DSPLD
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EPLA
Answer
Correct Answer: PAL
Explanation
Introduction / Context:GAL (Generic Array Logic) devices were introduced as reprogrammable, pin-compatible upgrades to popular PAL parts. Recognizing this lineage helps when replacing obsolete PALs in legacy designs.
Given Data / Assumptions:
- Part referenced: GAL16V8.
- PAL devices used a programmable AND array and fixed OR array.
- GALs maintain similar macrocell structures but allow reprogramming.
Concept / Approach:The GAL16V8 mirrors the PAL16V8’s I/O architecture and macrocell style, enabling drop-in replacement in many circuits. PROMs and PLAs have different internal organizations (PROM: fixed decoder with programmable outputs; PLA: both arrays programmable).
Step-by-Step Solution:
Identify GAL as a PAL-compatible technology with EEPROM cells.Note pin/function compatibility with popular PAL packages.Conclude the closest match is the PAL family.Verification / Alternative check:Datasheets list PAL-to-GAL migration guidance, including macrocell modes (combinational/registered) and output enable behavior.
Why Other Options Are Wrong:
- PROM: Memory-oriented, different internal structure.
- PLD/SPLD (generic): True categories, but the question asks for the most similar specific family.
- PLA: Both arrays programmable, unlike PAL/GAL pairing.
Common Pitfalls:Assuming all SPLDs are interchangeable; ignoring pin-compatibility and macrocell mode details when substituting parts.
Final Answer:PAL