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Questions and Answers
What is an interrupt service routine (ISR)?
What is an interrupt service routine (ISR)?
- A signal to the CPU to stop processing.
- A structure that saves registers.
- A program that handles the interrupt. (correct)
- A type of CPU register.
Interrupts can only be handled if no other programs are running.
Interrupts can only be handled if no other programs are running.
False (B)
What happens to the current register values when an interrupt occurs?
What happens to the current register values when an interrupt occurs?
They are saved onto a stack.
Higher priority interrupts can interrupt lower priority ______.
Higher priority interrupts can interrupt lower priority ______.
Match the categories of interrupts with their descriptions:
Match the categories of interrupts with their descriptions:
Flashcards
Interrupt
Interrupt
A signal that tells the processor that another device or program needs attention.
Interrupt Service Routine (ISR)
Interrupt Service Routine (ISR)
A program that handles an interrupt.
Stack
Stack
A data structure that stores the values of the CPU registers when an interrupt occurs.
Pushing onto the stack
Pushing onto the stack
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Popping from the stack
Popping from the stack
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Study Notes
Interrupt Service Routine
- Interrupts are signals indicating that devices or programs require the processor's attention.
- The fetch-decode-execute cycle is modified to include interrupt checks.
- An interrupt service routine (ISR) is a program managing the interrupt.
CPU Register Handling
- The CPU holds registers containing data for the active program, including the program counter (PC) and instruction register (IR).
- When an interrupt occurs, current register values are saved on a stack.
- This process of saving register values is called pushing onto the stack.
Interrupt Handling and the Stack
- Handling an interrupt involves setting the program counter to the ISR's first instruction address.
- The ISR runs to completion.
- Restored register values from the stack resume the interrupted program.
Priority Interrupts
- Interrupts have varying priorities.
- High-priority interrupts can interrupt lower-priority ISRs.
- Lower-priority ISR's register values are pushed onto the stack, enabling the higher-priority ISR's execution.
- After the higher-priority ISR's completion, the stack retrieves and restores lower-priority ISR's register values, continuing execution.
Interrupt Examples
- Ctrl+Alt+Delete or power button presses are high-priority interrupts.
- Used to recover from CPU-locked situations.
Categories of Interrupts
- Various interrupt types exist in PC architectures.
- Common interrupt categories include:
- Timer interrupts
- Device interrupts
- Software interrupts
- Hardware interrupts
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Description
This quiz covers the concepts of Interrupt Service Routine (ISR) and the handling of CPU registers during interrupts. It explores the expanded fetch-decode-execute cycle, the role of the stack in saving register values, and how the CPU resumes program execution after interrupts. Test your understanding of these essential computing topics!
