Hardware interrupt

Definition

A hardware interrupt is a signal sent from a hardware device to the CPU, indicating that it requires attention. This mechanism allows hardware devices, such as keyboards, mice, and disk drives, to communicate with the processor efficiently, ensuring timely responses to events like user input or data availability. By using interrupts, systems can prioritize tasks and improve overall efficiency, allowing the CPU to focus on other operations while waiting for events to occur.

5 Must Know Facts For Your Next Test

1. Hardware interrupts allow devices to signal the CPU without requiring constant attention, making operations more efficient.
2. There are two main types of hardware interrupts: maskable (can be ignored) and non-maskable (cannot be ignored).
3. When a hardware interrupt occurs, the CPU pauses its current task, saves its state, and executes the corresponding interrupt handler.
4. Interrupts can be prioritized, allowing more urgent requests to be processed before less critical ones.
5. Proper handling of hardware interrupts is crucial for real-time systems, where timing and quick responses are essential.

Review Questions

• How do hardware interrupts enhance system efficiency compared to polling?
  • Hardware interrupts enhance system efficiency by allowing devices to signal the CPU only when they need attention, rather than requiring the CPU to constantly check their status through polling. This reduces CPU workload and power consumption, as the processor can focus on other tasks instead of waiting for devices to respond. With interrupts, the system can respond immediately to events, improving responsiveness and performance.
• What is the role of an interrupt handler in the context of hardware interrupts?
  • An interrupt handler is a specific routine within the operating system that is executed in response to a hardware interrupt. When an interrupt occurs, the CPU temporarily halts its current task and transfers control to this handler. The handler processes the interrupt by executing necessary actions, such as reading data from a device or updating system state. After completing these tasks, control is returned to the original process, ensuring smooth operation.
• Evaluate how prioritization of hardware interrupts can affect system performance and real-time capabilities.
  • Prioritization of hardware interrupts plays a critical role in system performance and real-time capabilities by allowing more urgent tasks to be processed first. In scenarios where multiple devices signal at once, high-priority interrupts can preempt lower-priority ones, ensuring timely responses to critical events such as user inputs or time-sensitive data processing. This prioritization is essential in real-time systems where delays can lead to failure or degraded performance; it ensures that important tasks are handled promptly without being delayed by less critical operations.

Related terms

Polling: A method where the CPU repeatedly checks the status of a device at regular intervals to see if it needs attention.

Interrupt Handler: A special routine in the operating system that processes the hardware interrupt and executes the necessary actions.

Context Switching: The process of storing the state of a currently running process so that it can be resumed later, often triggered by an interrupt.