When a PC computer device wants to communicate with the processor, which system resource does it use?

Question

Options

• AI/O
• BDMA
• CPIO
• DIRQ

• A
  3% (1)
• B
  6% (2)
• D
  91% (30)

Explanation

IRQ (Interrupt Request) is the system resource a device uses to signal the processor that it needs attention - when a keyboard, NIC, or any peripheral needs the CPU to respond, it sends an IRQ signal to "interrupt" the processor and request service.

Why the distractors are wrong:

• A. I/O - I/O ports are the addresses used to transfer data to/from a device, not the mechanism for alerting the CPU.
• B. DMA - Direct Memory Access allows devices to transfer data directly to RAM without CPU involvement, bypassing the processor rather than communicating with it.
• C. PIO - Programmed I/O is a data transfer method where the CPU manually manages each transfer; it describes how data moves, not how a device requests CPU attention.

Memory tip: Think of IRQ = "I Request (your attention)" - just like raising your hand in class to get the teacher's attention, a device raises an IRQ line to interrupt the processor and say "I need you now."

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