GAL16V8 OLMC feedback path: In the Output Logic Macrocell, the FMUX selects which signal is fed back into the device’s input matrix. Assess whether this description is accurate for the GAL16V8 architecture.
Digital Electronics
Programmable Logic Device
Difficulty: Easy
Choose an option
Answer
Correct Answer: Correct
Explanation
Introduction / Context: Generic Array Logic (GAL) devices such as the GAL16V8 organize logic around Output Logic Macrocells (OLMCs). A key feature is a feedback multiplexer (often labeled FMUX) that determines what signal is returned to the AND array (input matrix) for building more complex equations.
Given Data / Assumptions:
- GAL16V8 OLMCs support combinatorial and registered modes.
- Feedback can source from the macrocell output, internal node, or registered output depending on mode.
- The FMUX selects the feedback source that re-enters the input matrix (AND array).
Concept / Approach: The feedback path enables product terms in one macrocell to reference the result of another, supporting multi-level logic within the constraints of a PLA-like structure. The FMUX is the selector that chooses which internal signal is fed back.
Step-by-Step Solution:
Identify OLMC components: product-term OR, optional register, output buffer, feedback mux.Confirm FMUX role: chooses feedback source (registered or combinatorial).Therefore, the statement matches the architecture → accurate.Verification / Alternative check:
Consult a GAL16V8 functional block diagram; a selectable feedback path to the AND array is clearly shown.Why Other Options Are Wrong:
Incorrect: Contradicts documented macrocell behavior.Only true for registered mode: Feedback exists for both modes (source differs).Applies only to active-LOW paths: Polarity control is separate from feedback selection.Common Pitfalls:
Assuming feedback always equals the pin state; internal selection may differ.Confusing input matrix (AND plane) with external pin routing.Final Answer:
Correct