What is interrupts ?

Interrupts

In system programming, an interrupt is a signal to the processor emitted by hardware or software indicating an event that needs immediate attention. An interrupt alerts the processor to a high-priority condition requiring the interruption of the current code the processor is executing. The processor responds by suspending its current activities, saving its state, and executing a function called an interrupt handler (or an interrupt service routine, ISR) to deal with the event. This interruption is temporary, and, after the interrupt handler finishes, the processor resumes normal activities.

There are two types of interrupts:

• Hardware Interrupts: These are used by devices to communicate that they require attention from the operating system.Internally, hardware interrupts are implemented using electronic alerting signals that are sent to the processor
• Software Interrupts: These are caused either by an exceptional condition in the processor itself, or a special instruction in the instruction set which causes an interrupt when it is executed

Each interrupt has its own interrupt handler. The number of hardware interrupts is limited by the number of interrupt request (IRQ) lines to the processor, but there may be hundreds of different software interrupts. Interrupts are a commonly used technique for computer multitasking, especially in real-time computing. Such a system is said to be interrupt-driven.

Interrupt handler: an interrupt handler, also known as an interrupt service routine or ISR, is a special block of code associated with a specific interrupt condition. Interrupt handlers are initiated by hardware interrupts, software interrupt instructions, or software exceptions, and are used for implementing device drivers or transitions between protected modes of operation, such as system calls.An interrupt handler is a low-level counterpart of event handlers.