Hardware interrupt

Definition

A hardware interrupt is a signal sent to the processor by hardware devices, indicating that an event needs immediate attention. This mechanism allows the CPU to respond promptly to important events, such as input from a keyboard or mouse, thereby improving the overall efficiency and responsiveness of a system. Hardware interrupts are essential for managing multiple tasks and ensuring that time-sensitive processes are prioritized effectively.

5 Must Know Facts For Your Next Test

1. Hardware interrupts can be triggered by various events such as timer expirations, input from peripherals, or communication signals from other devices.
2. They enable asynchronous processing, allowing the CPU to perform other tasks while waiting for an event to occur.
3. Each hardware interrupt typically has a unique interrupt request (IRQ) number to identify the source of the interrupt.
4. When a hardware interrupt occurs, the CPU saves its current state before executing the corresponding ISR, ensuring that it can return to its previous task afterward.
5. Hardware interrupts are crucial in real-time systems where timely responses to events are necessary for proper functionality.

Review Questions

• How do hardware interrupts improve system efficiency compared to polling?
  • Hardware interrupts improve system efficiency by allowing devices to notify the CPU only when they need attention, rather than having the CPU constantly check device status as in polling. This means that the CPU can focus on executing other tasks without wasting cycles on unnecessary checks. As a result, resources are used more effectively, leading to better performance and responsiveness in managing multiple operations.
• What role do Interrupt Service Routines (ISRs) play in handling hardware interrupts?
  • ISRs are crucial for managing hardware interrupts as they contain the specific instructions executed when an interrupt is received. When a hardware interrupt occurs, the CPU temporarily halts its current execution context and jumps to the ISR associated with that interrupt. This allows for efficient handling of the event that caused the interrupt, ensuring that important tasks are addressed quickly while maintaining system stability.
• Evaluate how priority levels influence the handling of multiple hardware interrupts in a complex embedded system.
  • Priority levels significantly influence how an embedded system manages multiple hardware interrupts by determining which interrupts are serviced first based on their urgency. In a scenario with concurrent interrupts, higher priority interrupts can preempt lower priority ones, ensuring critical tasks are executed without delay. This hierarchical management allows systems to maintain responsiveness and stability, especially under heavy load or when dealing with time-sensitive operations, ultimately enhancing overall system performance.

Related terms

Interrupt Service Routine (ISR):

A special function that executes in response to a hardware interrupt, allowing the system to address the event that triggered the interrupt.

Polling:

A technique where the CPU repeatedly checks the status of a device at regular intervals to see if it needs attention, in contrast to hardware interrupts which allow devices to signal their needs.

Priority Levels: A classification system for interrupts that determines the order in which different interrupts are serviced based on their urgency and importance.