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23. Introduction to Interrupt

This chapter discusses the concept of interrupts in computing, detailing how they allow the system to interrupt regular instruction execution to handle urgent tasks. It explains the execution flow concerning program counters, the handling of instruction service routines, and the instruction cycle phases such as fetch, decode, execute, and checking for interrupts. Examples illustrating simple instruction execution and their interaction with memory are also provided.

Sections

Interrupt

This section discusses the concept of interrupts in instruction execution and their significance in managing hardware and I/O operations.

23.1 Section Overview

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23.1.1 Introduction to Interrupt

This section introduces the concept of interrupts in computer architecture, explaining how they alter the normal flow of code execution in response to external events.

23.1.2 Handling Interrupts

This section explains the concept and handling of interrupts in instruction execution, detailing how program counter values are managed during an interrupt service routine.

23.1.3 Interrupt Service Routine

The Interrupt Service Routine (ISR) is a critical mechanism in computer systems that manages interrupts to ensure smooth instruction execution.

Instruction Execution Flow

This section explains how instruction execution is interrupted and serviced in computer systems, detailing the flow of code management.

23.2 Section Overview

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23.2.1 Fetch Phase

The Fetch Phase in computing involves the execution of instructions, checks for interrupts, and manages program counter values for efficient code execution.

23.2.2 Decode Phase

The Decode Phase focuses on the interrupt handling process, detailing how the CPU responds to interrupts during instruction execution, ensuring that execution can resume seamlessly.

23.2.3 Execute Phase

The Execute Phase involves the handling of interrupts and the execution of instructions through a systematic process of saving, branching, and restoring the program counter.

23.2.4 Operand Address Calculation

This section discusses the process of Operand Address Calculation, focusing on instruction sequences, interrupts, and how program counters operate during instruction execution.

23.2.5 Checking for Interrupts

This section explores the concept of interrupts in programming, explaining how the normal flow of instructions can be disrupted by urgent hardware or I/O events that require immediate attention.

Instruction Cycle Code (ICC)

The Instruction Cycle Code (ICC) facilitates the flow and control of instruction execution phases in computing.

23.3 Section Overview

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23.3.1 Phases of Instruction Cycle Code

This section introduces the various phases of the instruction execution cycle, focusing on interrupts and the instruction cycle code.

23.3.2 Immediate vs. Non-immediate Addressing

This section discusses the concepts of immediate and non-immediate addressing in instruction execution and the functionality of interrupt servicing.

23.3.3 Direct and Indirect Addressing

This section explains the concepts of direct and indirect addressing in the context of instruction execution, including how interrupt handling affects the program counter.

Example of Instruction Execution

This section discusses the concept of interrupts in instruction execution and the lifecycle of an instruction from fetching to execution and servicing interrupts.

23.4 Section Overview

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23.4.1 Memory Locations and Instructions

This section covers the mechanism of instruction execution through interrupts, the role of the program counter, and the process of servicing interrupts.

23.4.2 Step-by-Step Code Execution

This section explains the concept of interrupts in instruction execution and the process of managing program counters during these events.

Conclusion and Objectives

This section outlines the execution of indirect instructions through interrupts and presents key objectives of the instructional phase.

23.5 Section Overview

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23.5.1 Objectives of the Unit

The section outlines the objectives of the unit concerning instruction execution and interruptions.

23.5.2 Next Steps in Learning

The section explains the concept of interrupts in instruction execution and the role of the Instruction Cycle Code (ICC) in managing various instruction phases.

Learning Objectives

  • Interrupts are essential for managing urgent hardware and I/O tasks within a computing system.

  • The instruction cycle includes phases of fetching, decoding, executing, and handling interrupts.

  • Understanding how to save and restore the program counter and register states is crucial for effective interrupt handling.

Key Concepts

Interrupt

A mechanism that allows a hardware or software event to pause the current execution flow and execute a designated interrupt service routine.

Program Counter (PC)

A register that indicates the address of the next instruction to be executed in a program.

Instruction Cycle Code (ICC)

A two-bit code used to indicate the current phase of instruction processing such as fetching, decoding, execution, or servicing an interrupt.

Instruction Service Routine (ISR)

A specific code segment designed to handle the operations necessary when an interrupt occurs.

Practice Exercises

Total Questions

2

Estimated Time

4 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting