Three-state buffer purpose in bus systems What is the primary purpose of using a three-state (tri-state) buffer in a shared data bus architecture?

Introduction / Context:
In bused systems, many devices share lines. A three-state buffer lets only one device drive the bus at a time, preventing contention. Understanding its primary role helps in designing reliable bus interfaces.

Given Data / Assumptions:

• Shared data bus with multiple potential drivers.
• Buffers can be enabled or disabled to present high impedance.

Concept / Approach:
Tri-state buffers have an enable control. When enabled, they pass data; when disabled, they present a high-impedance output (effectively disconnected). This gating of drive onto the bus is fundamentally about controlling data flow and bus access.

Step-by-Step Solution:

Verification / Alternative check:
System timing diagrams show OE (output enable) signals orchestrating which device drives the bus in each time slot—core to data flow control.

Why Other Options Are Wrong:

• Isolation (a): A tri-state does isolate when disabled, but isolation is a consequence; the primary system-level goal is controlled data flow.
• Provide sink/source current (b): That is a line-driver strength consideration, not the defining purpose of tri-state behavior.
• Temporary storage (c): Buffers do not store like latches/flip-flops.

Common Pitfalls:

• Equating tri-state drivers with simple buffers and overlooking the OE-controlled high-Z state.

Final Answer:
to control data flow