TTL troubleshooting scenario: An inverter (NOT gate) drives one input of a 2-input AND gate. If the inverter’s output lead is open (disconnected due to a fault) and logic pulses are applied at the other AND input (point B), what will appear at the AND output?

Introduction / Context:
Floating nodes behave differently in TTL than in CMOS. In classic TTL, an unused or open TTL input tends to read as logic HIGH due to internal bias currents. This behavior influences fault outcomes when a driving output lead is broken.

Given Data / Assumptions:

• Standard two-input TTL AND gate.
• One AND input is driven by an inverter whose output lead is open (disconnected).
• The other AND input (point B) carries logic pulses.
• No external pull resistors changing the default bias.

Concept / Approach:
With the inverter’s output lead open, the AND input it should drive is effectively floating. In TTL, a floating input biases HIGH. Therefore, the AND gate effectively sees one input fixed at HIGH, and the output follows the other input.

Step-by-Step Solution:
1) Open output leaves the receiving AND input floating.2) Floating TTL input defaults to HIGH.3) AND truth: X * 1 = X.4) With point B pulsing, the AND output reproduces the pulses.

Verification / Alternative check:
Consult standard TTL input characteristics showing that an unconnected input is read as HIGH, unlike CMOS which is high-impedance and undefined without biasing.

Why Other Options Are Wrong:
“a steady LOW/HIGH” ignore that the pulsing input propagates when the other input is effectively HIGH; “an undefined level” is more typical of CMOS or analog float, not classic TTL inputs.

Common Pitfalls:
Assuming CMOS-like undefined behavior; overlooking that the failure is the driver lead, not the AND gate pin itself.

Final Answer:
pulses