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Summary of Section 12.1 - C191: Operating Systems for Programmers (zyBooks)

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Introduction

A computer's primary tasks involve Input/Output (I/O) operations and computing, with I/O often being the dominant function. Activities such as web browsing and file editing emphasize data input and retrieval rather than complex computations.

The operating system (OS) plays a crucial role in managing and controlling I/O operations and devices. This section consolidates I/O-related topics to provide a complete overview. The discussion is structured as follows:

1. I/O Hardware Basics – Understanding hardware constraints and their impact on OS design.
2. I/O Services of the OS – How the OS provides and integrates I/O functionalities.
3. Bridging the Hardware-Application Gap – The OS mediates between low-level hardware and high-level application interfaces.
4. UNIX System V STREAMS Mechanism – A method for dynamically assembling pipelines of driver code.
5. I/O Performance Considerations – Optimizing OS design to enhance I/O performance.

Chapter Objectives

• Examine the structure of an OS's I/O subsystem.
• Discuss the complexities and principles of I/O hardware.
• Analyze performance aspects of both I/O hardware and software.

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Summary of Section 12.2 - C191: Operating Systems for Programmers (zyBooks)

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Overview

Managing I/O devices is a crucial responsibility of operating system (OS) designers due to the wide range of device types, speeds, and functions (e.g., mouse, hard disk, flash drive, tape robot). The I/O subsystem within the kernel abstracts the complexities of handling these devices.

Two contrasting trends shape I/O-device technology: