Computer Architecture Questions Long
Interrupt handling is a crucial aspect of computer architecture that allows the system to respond to external events or internal conditions that require immediate attention. An interrupt is a signal generated by a device or a program that interrupts the normal execution flow of the processor, prompting it to temporarily suspend its current task and switch to a different task or subroutine.
The concept of interrupt handling involves several components and processes that work together to ensure efficient and timely response to interrupts. These components include interrupt requests (IRQs), interrupt service routines (ISRs), interrupt vectors, and interrupt controllers.
When an interrupt occurs, it is typically initiated by an external device such as a keyboard, mouse, or disk controller, or by an internal event such as a divide-by-zero error or a timer expiration. The device or event generating the interrupt sends an interrupt request (IRQ) signal to the processor, indicating the need for attention.
Upon receiving an IRQ, the processor suspends its current execution and saves the necessary information about the interrupted task, such as the program counter and register values, onto the stack. It then looks up the interrupt vector, which is a table or a data structure that maps each interrupt to its corresponding interrupt service routine (ISR).
The interrupt vector provides the address of the ISR, which is a specific routine or subroutine designed to handle the interrupt. The processor jumps to the address specified by the ISR and begins executing the ISR code. The ISR performs the necessary actions to handle the interrupt, such as reading data from the device, updating system status, or initiating a response.
Once the ISR completes its execution, it returns control back to the interrupted task by restoring the saved program counter and register values from the stack. The interrupted task resumes its execution from the point where it was interrupted, as if the interrupt never occurred.
To manage multiple interrupts efficiently, modern computer architectures employ interrupt controllers. These controllers prioritize interrupts based on their urgency or importance and ensure that the processor handles them in the appropriate order. Interrupt controllers also allow for masking or disabling certain interrupts to prevent them from interrupting critical tasks.
In summary, interrupt handling in computer architecture involves the detection of interrupts, saving the state of the interrupted task, identifying the appropriate ISR through interrupt vectors, executing the ISR to handle the interrupt, and returning control to the interrupted task. This mechanism enables the system to respond promptly to external events and internal conditions, enhancing the overall functionality and responsiveness of the computer system.