SPLD classification scope: Within the broad PLD landscape (SPLD, CPLD, FPGA), which class specifically covers the smallest, earliest-generation programmable logic devices such as PALs and GALs?

Difficulty: Easy

Correct Answer: smallest

Explanation:


Introduction / Context:
Programmable Logic Devices (PLDs) are grouped into classes: SPLD (Simple PLD), CPLD (Complex PLD), and FPGA (Field-Programmable Gate Array). Recognizing what each class includes helps designers choose the right device for logic density, speed, and cost.



Given Data / Assumptions:

  • SPLD stands for Simple Programmable Logic Device.
  • Examples include PALs (Programmable Array Logic) and GALs (Generic Array Logic).
  • Device scale and capability range upward from SPLD → CPLD → FPGA.


Concept / Approach:
SPLDs were the earliest widely used PLDs and are also the smallest in logic capacity. They typically provide a programmable AND with fixed OR (PAL) or both AND/OR programmable (PLA variants), and a limited number of macrocells and I/O pins. They are ideal for glue logic and small decoders/encoders.



Step-by-Step Solution:

Identify SPLD definition → Simple devices (PAL/GAL/PLA).Contrast with CPLD/FPGA → much larger resources, routing, and features.Therefore, SPLD class includes the “smallest” devices.


Verification / Alternative check:

Textbooks and vendor taxonomies list PAL/GAL under SPLD, confirming their small scale and early adoption.


Why Other Options Are Wrong:

earliest: Historically true, but the classification keyword sought is size/capacity, not chronology.largest: Largest belongs to modern FPGAs.newest: Newest devices are advanced CPLDs and FPGAs, not SPLDs.


Common Pitfalls:

Equating “earliest” with the answer; the taxonomy is about device scale.Assuming SPLD is a language or software feature rather than a device class.


Final Answer:

smallest

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