In Interrupt-Initiated I/O, how does the CPU know which device requested an interrupt in Vectored Interrupt mode?

Subject: Computer Architecture and Organization

Topic: Input-Output (I/O) Organization & DMA

Options:

1. Option A: The interrupting device supplies an interrupt vector number/address over the data bus during INTA cycle
2. Option B: CPU polls every device one by one in software loop
3. Option C: CPU reads the hard drive partition table
4. Option D: Device lights an LED indicator on motherboard

Correct Answer:

Option A: The interrupting device supplies an interrupt vector number/address over the data bus during INTA cycle

Explanation:

In Vectored Interrupts, the device places its unique vector identifier/address on the data bus when it receives INTA (Interrupt Acknowledge) from CPU.