(c) What is an Interrupt? Why are interrupts used in a computer? Explain different kinds of interrupts. Also, explain the process of interrupt processing.

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  What is an Interrupt?

An interrupt is a mechanism that allows the normal sequence of program execution to be temporarily halted and transferred to a specific routine known as an interrupt service routine (ISR) or interrupt handler. Interrupts are events that require immediate attention from the processor.

Why are Interrupts Used?

1. Handling External Events:

   - Interrupts are used to handle external events or signals that occur outside the normal flow of program execution. Examples include hardware signals, I/O completion, or timer events.

2. Real-Time Responsiveness:

   - Interrupts provide a way for a computer system to respond promptly to external events, making it suitable for real-time systems.

3. Efficient Resource Utilization:

   - Interrupts allow the processor to perform other tasks while waiting for external events, improving overall system efficiency.

Different Kinds of Interrupts:

1. Hardware Interrupts:

   - Generated by external hardware devices to request attention from the processor. Examples include I/O interrupts, timer interrupts, and error interrupts.

2. Software Interrupts:

   - Invoked by software instructions to request specific services or operations. Often used for system calls or to signal specific events.

3. Maskable Interrupts:

   - Interrupts that can be temporarily disabled (masked) by the processor. The decision to mask or unmask these interrupts depends on the current state of the system.

4. Non-Maskable Interrupts (NMI):

   - Interrupts that cannot be disabled or masked by the processor. They usually indicate critical system errors that require immediate attention.

 Process of Interrupt Processing:

1. **Interrupt Request (IRQ):**

   - An external event occurs, and an interrupt request is generated. This could be a hardware device signaling completion, a timer reaching zero, or other events.

2. **Interrupt Controller:**

   - The interrupt controller prioritizes and manages multiple interrupt requests if present. It informs the processor about the highest-priority pending interrupt.

3. Interrupt Handling:

   - The processor saves the current state of the program (registers, program counter) and transfers control to the appropriate interrupt service routine (ISR).

4. Interrupt Service Routine (ISR):

   - The ISR is a specific routine designed to handle the interrupt. It performs the necessary tasks associated with the interrupt, such as updating data or responding to a hardware event.

5. Context Switch:

   - The processor may need to switch between the interrupted task and the ISR. This involves saving the interrupted task's context and restoring it after the ISR execution.

6. **Return from Interrupt (RTI):

   - After the ISR completes its tasks, a return-from-interrupt instruction is executed. This restores the saved context, allowing the interrupted task to resume.

Interrupts are crucial for efficient multitasking, real-time processing, and handling diverse events in computer systems. They enhance the responsiveness and flexibility of the system architecture.

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