I/O port behavior — which statement is correct? In programmable I/O systems, what access directions can a port support depending on design and configuration?

Introduction / Context:
Microcontrollers and peripheral interfaces expose ports that connect the digital world to sensors, actuators, and other chips. The direction of data flow at a port pin depends on the hardware design and configuration registers controlled by software.

Given Data / Assumptions:

• Some ports are input-only (for example, ADC inputs or dedicated status lines).
• Some ports are output-only (for example, certain driver lines or write-only latches).
• Many general-purpose I/O ports are configurable as input or output, sometimes per pin.

Concept / Approach:

Because real systems include all three port types (input-only, output-only, and bidirectional), the most complete answer is that a port can be any of these depending on device and configuration. Configuration registers (for example, DDR/ TRIS/ DIR) often control direction on a per-bit basis in microcontrollers.

Step-by-Step Solution:

Verification / Alternative check:

Datasheets for GPIO modules document input, output, and bidirectional settings, including pull-ups, pull-downs, and open-drain or push-pull modes.

Why Other Options Are Wrong:

Each single-direction option is incomplete; real devices support multiple configurations across different ports or pins.

Common Pitfalls:

Assuming all ports are symmetrical; some pins have alternate functions or electrical limits that restrict direction or drive strength.

Final Answer:

all of the above