Programmable logic devices (PLDs) — which device types can implement basic custom logic functions? In the context of digital design, identify which category of PLD can be used to program and realize simple combinational and/or sequential logic functions on hardware.

Introduction / Context:
Programmable logic devices (PLDs) provide field-configurable hardware for implementing digital logic without fabricating a custom chip. This question checks whether you recognize that multiple PLD families—Programmable Logic Arrays (PLA), Programmable Array Logic (PAL), and Complex PLDs (CPLD)—can all implement basic logic functions such as decoders, state machines, and glue logic.

Given Data / Assumptions:

• PLA devices have programmable AND and programmable OR arrays.
• PAL devices typically have a programmable AND array and a fixed OR array, with optional output polarity control.
• CPLDs combine many PAL/PLA-like macrocells with routing to realize larger designs.

Concept / Approach:
Any device that provides user-programmable product terms (AND terms) and a way to sum them (OR terms), with optional registers, can implement basic logic functions. PLAs and PALs are the classical building blocks for small to medium functions, whereas CPLDs scale these ideas into larger, more integrated packages. Therefore, all three can be used to implement simple logic safely and effectively.

Step-by-Step Solution:

Verification / Alternative check:
Vendor datasheets (e.g., classic PAL/GAL parts and CPLD families like MAX7000 or XC9500) explicitly show sum-of-products structures that implement the same fundamental logic forms taught in digital design courses.

Why Other Options Are Wrong:

• PLA only: too narrow—PAL and CPLD also work.
• PAL only: ignores PLA and CPLD capabilities.
• CPLD only: ignores that smaller PLDs can do the same basics.

Common Pitfalls:
Assuming “CPLD” is needed for everything; for small tasks, a PLA/PAL (or GAL) is often simpler and cheaper.

Final Answer:
all the above