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What are IRQs (Interrupt Requests)? Introducing the Basic Concepts of Computer Interrupts
Interrupts are an essential part of modern computer systems that allow for efficient handling of various events and tasks. Among the various types of interrupts, IRQs, or Interrupt Requests, play a crucial role in enabling devices to communicate with the CPU and obtain its attention when necessary.
Understanding Interrupts
In computer systems, an interrupt is a signal sent to the processor by an external device or internal software to request its attention and interrupt its current execution. The primary purpose of interrupts is to handle time-critical events or tasks in a prompt and efficient manner. By using interrupts, devices can avoid constant polling of the CPU and, instead, receive the necessary attention to complete their tasks when required.
Introduction to IRQs
IRQs are a specific type of interrupt that is used to manage and prioritize external device requests within a computer system. Each IRQ is assigned a unique number, typically ranging from 0 to 15, which helps in identifying the source of the interrupt. These IRQ numbers are known as interrupt lines.
When a device needs the CPU’s attention, it sends an interrupt signal through the corresponding interrupt line. The processor then acts on the interrupt request by suspending its current execution and responding to the device’s needs. Once the device’s request is handled, the CPU resumes its previous execution.
IRQ Management and Priority
IRQs allow for efficient handling of various external events, such as keyboard input, mouse movements, or data transfer requests from peripherals like hard drives or network cards. To ensure smooth operation of the system, IRQs are managed through a priority system.
In most modern computer systems, IRQs are handled by a programmable Interrupt Controller (PIC). The PIC prioritizes and manages the incoming interrupts, ensuring the CPU responds to the most critical events first. Each device connected to the system is assigned a specific IRQ, and the PIC handles the routing and interruption of the CPU to the appropriate device when necessary.
Conclusion
IRQs, or Interrupt Requests, are an integral part of computer systems that enable devices to communicate with the CPU efficiently. By managing and prioritizing external device requests, IRQs help ensure prompt handling of critical events and tasks. Understanding the basics of IRQs and how interrupts work in general gives us a glimpse into the inner workings of modern computing, underscoring the significance of seamless communication between devices and the CPU.
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