2.1.7

Interrupt Service Routine (ISR)

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Interrupt Service Routine (ISR)

An interrupt service routine is a set of instructions that need to be done as part of an interrupt.

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ISR

  • An interrupt service routine is a set of instructions that need to be done as part of an interrupt.
  • When an interrupt service routine has been completed, the CPU will go back to the set of instructions it was doing before.
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Process

  • As an interrupt arrives at the CPU it comes with a flag to indicate the priority of the interrupt.
  • This interrupt could be higher importance than the set of instructions it is currently working.
  • The interrupt pushes the current instruction and all the contents of the registers in the CPU to a stack.
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Process cont.

  • The CPU will then complete the interrupt service routine and then load the registers back in from the stack and continue where it left off.
  • At the end of each fetch, decode, execute cycle, the CPU checks for interrupts and their priorities before continuing on.

Jump to other topics

1Components of a Computer

2Software & Software Development

3Exchanging Data

4Data Types, Data Structures & Algorithms

5Legal, Moral, Cultural & Ethical Issues

6Elements of Computational Thinking

6.1Thinking Abstractly

6.2Thinking Ahead

6.3Thinking Procedurally

6.4Thinking Logically

6.5Thinking Concurrently

7Problem Solving & Programming

8Algorithms

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