28 Lecture - Interrupt Hardware and Software

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28 Lecture

CS501

Midterm & Final Term Short Notes

Interrupt Hardware and Software

Interrupts can be classified into two categories: hardware interrupts and software interrupts. Hardware interrupts are generated by external events such as I/O devices signaling the CPU. Software interrupts, also known as traps, are generated by


Important Mcq's
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  1. Which of the following is an example of a hardware interrupt? a) System call b) Division by zero c) Keyboard press d) Memory access violation Answer: c) Keyboard press Which of the following is an example of a software interrupt? a) Disk read error b) Mouse click c) System call d) Power outage Answer: c) System call Which type of interrupt is triggered by a device? a) Hardware interrupt b) Software interrupt c) Both d) None Answer: a) Hardware interrupt Which type of interrupt is triggered by a program instruction? a) Hardware interrupt b) Software interrupt c) Both d) None Answer: b) Software interrupt Which of the following is an example of a hardware interrupt controller? a) BIOS b) DMA controller c) CPU d) Memory Answer: b) DMA controller Which of the following is an example of a software interrupt handler? a) Device driver b) Interrupt service routine (ISR) c) Interrupt vector table d) Interrupt request (IRQ) Answer: b) Interrupt service routine (ISR) Which type of interrupt has higher priority? a) Hardware interrupt b) Software interrupt c) Both have equal priority d) It depends on the system design Answer: a) Hardware interrupt Which of the following is responsible for managing the interrupt requests in a system? a) Interrupt service routine b) Interrupt handler c) Interrupt controller d) Interrupt vector table Answer: c) Interrupt controller Which type of interrupt can be masked or disabled? a) Hardware interrupt b) Software interrupt c) Both d) None Answer: a) Hardware interrupt Which type of interrupt can be triggered by a user-level program? a) Hardware interrupt b) Software interrupt c) Both d) None Answer: b) Software interrupt


Subjective Short Notes
Midterm & Finalterm Prepration
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  1. What is a hardware interrupt, and how is it triggered? Answer: A hardware interrupt is a signal sent by an external device to the CPU to request its attention. It is triggered when an external event occurs, such as a keyboard press or a network packet arriving. What is a software interrupt, and how is it triggered? Answer: A software interrupt, also known as a trap, is an interrupt triggered by a software instruction. It is triggered when a program executes a specific instruction, such as a system call. What is an interrupt service routine (ISR)? Answer: An interrupt service routine (ISR) is a piece of code that handles the interrupt request when an interrupt is triggered. It is executed when the CPU receives an interrupt signal. What is an interrupt vector table, and how is it used? Answer: An interrupt vector table is a data structure that stores the memory address of the ISR for each interrupt type. It is used by the CPU to locate the appropriate ISR when an interrupt occurs. What is an interrupt controller, and what is its function? Answer: An interrupt controller is a device that manages the interrupt requests generated by external devices. Its function is to prioritize and route the interrupt requests to the appropriate processor. What is the difference between a maskable and non-maskable interrupt? Answer: A maskable interrupt is one that can be temporarily disabled by the CPU, while a non-maskable interrupt cannot be disabled. Non-maskable interrupts are typically used for critical system events, such as hardware failures. What is the priority of hardware interrupts compared to software interrupts? Answer: Hardware interrupts have higher priority than software interrupts. This is because hardware interrupts are triggered by external devices and require immediate attention. What is the purpose of an interrupt handler? Answer: An interrupt handler is responsible for managing the interrupt request and executing the ISR. It performs tasks such as saving the CPU context and restoring it after the ISR is complete. How does the CPU handle multiple interrupt requests? Answer: The CPU prioritizes interrupt requests based on their level of urgency. When multiple interrupts occur simultaneously, the CPU uses an interrupt controller to determine the highest priority interrupt and executes its ISR. What is an interrupt request (IRQ), and how is it used? Answer: An interrupt request (IRQ) is a signal sent by an external device to request the CPU's attention. It is assigned a unique number, which is used to identify the interrupt source and locate the appropriate ISR in the interrupt vector table.

Interrupts are a fundamental concept in computer architecture that enable the CPU to handle external events asynchronously. Interrupts can be classified into two categories: hardware interrupts and software interrupts. Hardware interrupts are generated by external devices such as keyboards, mice, network interfaces, and hard drives. When an external event occurs, the device sends an interrupt signal to the CPU to request its attention. The CPU then stops its current task and executes the Interrupt Service Routine (ISR) associated with the interrupt. Software interrupts, also known as traps, are triggered by software instructions rather than external events. Software interrupts are used to switch from user mode to kernel mode, perform system calls, and handle exceptions such as page faults and divide-by-zero errors. An Interrupt Vector Table (IVT) is used to manage interrupts in a system. The IVT is a data structure that stores the memory addresses of the ISR for each interrupt type. When an interrupt occurs, the CPU uses the interrupt number to index the IVT and locate the appropriate ISR. Interrupt controllers are devices that manage interrupt requests in a system. They prioritize and route interrupt requests to the appropriate processor. Interrupt controllers can also be used to mask or disable certain interrupts, allowing the system to focus on the most critical tasks. Interrupts can be either maskable or non-maskable. Maskable interrupts can be temporarily disabled by the CPU, while non-maskable interrupts cannot be disabled. Non-maskable interrupts are typically used for critical system events, such as hardware failures. In a multi-tasking system, multiple interrupts can occur simultaneously. To handle this situation, the CPU prioritizes the interrupts based on their level of urgency. The Interrupt Request (IRQ) line of the CPU is used to determine the highest priority interrupt, and the corresponding ISR is executed. In summary, interrupts are an essential component of computer architecture that enable the CPU to handle external events asynchronously. Interrupts can be classified into hardware interrupts and software interrupts, and are managed using an Interrupt Vector Table and Interrupt Controller. By prioritizing and handling interrupts efficiently, a system can perform multiple tasks simultaneously and respond to external events in a timely manner.

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