GAL vs PAL — reprogrammable logic: Is it correct to describe a GAL (Generic Array Logic) device as a programmable and reprogrammable successor to a PAL (Programmable Array Logic)?

Difficulty: Easy

Correct Answer: Correct

Explanation:


Introduction / Context:
PALs were early SPLDs that used one-time programmable fuses. GALs were later introduced to be pin-compatible with many PALs while providing EEPROM-based, electrically erasable configuration. This made GALs attractive drop-in, reprogrammable replacements in development and production.



Given Data / Assumptions:

  • PAL: programmable once (fuse-based), fixed OR array with programmable AND array.
  • GAL: EEPROM-based, electrically erasable and reprogrammable.
  • Many GALs support multiple program/erase cycles and security features.


Concept / Approach:
The functional model of GALs is similar to PALs (sum-of-products into macrocells), but GALs add reprogrammability and often macrocell configurability (for example, registered vs combinational). Thus, labeling GALs as programmable/reprogrammable PALs captures their role and compatibility in many designs.



Step-by-Step Solution:

Identify PAL limitations: one-time programmability.Identify GAL advantages: EEPROM-based, reprogrammable, secure, compatible footprints.Assess application impact: faster iteration, field updates, inventory simplification.Conclude the characterization is accurate.


Verification / Alternative check:
GAL datasheets describe electrical reprogramming cycles, pin compatibility, and macrocell options compared with classic PAL parts.



Why Other Options Are Wrong:

Incorrect: Contradicts the well-known purpose of GALs.UV-erasable / PROM-based qualifiers: GALs erase electrically; they are not PROM-only nor UV-dependent.


Common Pitfalls:
Assuming all SPLDs are one-time programmable; overlooking security bits and power/timing differences between PAL and GAL.


Final Answer:
Correct

More Questions from Programmable Logic Device

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion