Hardware Polling:

A method to identify the interrupting device among multiple I/O devices using hardware logic instead of software.

A dedicated polling unit / hardware poller sequentially interrogates (polls) each device's interrupt flag via a common bus. It checks status bits one-by-one in priority order using combinational/sequential polling logic.

• Faster than software polling (which uses program loop to test each device).
• Flexibility intermediate between daisy-chain and vectored interrupt.
• On finding the requesting device, its address/vector is placed on bus and ISR is executed.

Contrast: Software polling – CPU executes a program to poll each device; Hardware polling – special hardware does it automatically.