Operating system introduction and spiritual Analysis Introduction

Operating system introduction and spiritual Analysis Introduction

Address of this article: http://www.cnblogs.com/archimedes/p/os-introduction.html.

1. Why learning the operating system?

Master System Design in general

The operating system includes all software design/implementation issues, resource sharing/management, security and identity verification, flexibility, robustness, and user-friendly interface design.

There are a large number of "Operating Systems" that people cannot realize"

• Embedded Systems (PDA, mobile phone-WP7, Android, set-top box, etc)

• MINI-OS In the application system)

• In daily life, Windows operating systems (such as Unix, Linux, Apple Macintosh, and ibm OS/2) are not always used)

Many fields related to computer science:

• Computer Architecture/hardware

• Software Design

• Programming Language

• Data Structure

• Algorithm

• Abstraction

2. Objective/objective of the Operating System

Execute user programs and make user problems easier to solve.

Use resources in an effective way (effectiveness-the point of view of system administrators ).

Make Computer Systems easier to use (convenience-user's point of view ).

It adopts a new OS structure and is easy to add, delete, and modify functions (Scalable ).

A unified and open environment is required. Various types of computer hardware systems come from different manufacturers and can be integrated through networks and work together correctly and effectively to achieve application porting (openness ).

3. Composition of computer systems 1. Composition of computer systems

Hardware System (bare metal): CPU, memory (primary and secondary storage), I/O, I/O Control System

Software System: system software and application software

System software: manages the operations of the computer. Such as operating system and compiling system

Application Software: provides users with solutions. Such as scientific computing and transaction management

2. Hierarchy of computer systems

 

4. Functions of the Operating System

• OS acts as an interface between users and computer hardware systems

• Command Method

• System Call Method

• Graphics and window Modes

OS as the manager of computer system resources

Management objects include: CPU, memory, external devices, information (data and software );

Management content: the current status of resources (quantity and usage), resource allocation, recycling and access operations, corresponding management policies (including user permissions )......

OS abstracts computer resources

Add on bare metal: device management, file management, storage management (for memory and external storage), processor management (for CPU );

That is, the OS is used as the extended machine/virtual machine ).

5. Basic Features of the Operating System

• Concurrence)

• Sharing)

• Virtual)

• Asynchronism)

1. Concurrency: A Program (process) that runs multiple channels in a computer system at the same time)

MACRO: Multi-program execution at the same time

Microscopic: Only one program is executed at any time, that is, multiple programs take turns (Alternate) on the CPU (standalone)

Parallel (parallel): similar to concurrency, it means that multiple programs are executed at the same time, but multiple hardware support is required.

Introduction Process

Programs and processes: in multiple program systems, programs cannot run independently, and cannot be concurrently executed with other programs. The purpose of introducing a process is to make multiple programs run concurrently.

Import thread

A process is the basic unit in an operating system that has resources and runs independently. After a thread is introduced, the process is used as the basic unit for resource allocation, and the thread is used as the basic unit for independent operation and scheduling, further improving the concurrency of the system.

2. Share

Resources in the system are not exclusive to a program, but used by multiple programs.

Resource Sharing: mutual exclusion and simultaneous access

Concurrency and sharing are the two most basic features of the operating system, and they are mutually exists:

• Resource Sharing is based on concurrent execution of programs (processes.

• Concurrent execution of the program is also based on the sharing of resources.

3. Virtual

A certain technology is used to map a physical entity to several corresponding logical entities-time-sharing (time-division multiplexing) or space-separation (space-division multiplexing ).

Virtualization is an important means of operating system management system resources and can improve resource utilization. Such as: virtual processor (time-based), virtual device (time-based), virtual disk (space-based), virtual memory (space-based, time-based)

4. asynchronous

Uncertainty means that the execution time, sequence, forward speed, and completion time of a process are unpredictable during execution.

As long as a complete process synchronization mechanism is configured in the OS and the running environment is the same, the job will get the same results after multiple runs. Therefore, asynchronous running is allowed and is an important feature of OS.

6. Operating System Functions

Processor management, memory management, device management, file management, user interface

1. processor management

Main tasks of processor management:

• Is to allocate the processor

• Effective control and management of processor operations

Note: The distribution and operation of processing machines are based on processes. Therefore, management of processing machines can be attributed to management of processes.

Processor management functions

• Process Control
• Process Synchronization
• Process Communication
• Scheduling

2. Memory Management

Main Tasks:

• Provides a good environment for multi-program running
• Ease of use of memory
• Improves memory utilization
• Logically extended memory

Function:

• Memory Allocation (static and dynamic)
• Memory Protection
• Address ing
• Memory expansion

3. Main tasks of device management:

• Complete the I/O Request
• Allocate I/O devices to users
• Improve the utilization and speed of I/O devices
• Easy to use I/O devices

Function

• Buffer Management
• Device allocation
• Device Processing
• Virtual Device

4. File Management

Main Tasks

• Manage user files and system files
• Ease of use of Files
• Ensure file security

Function:

• File read/write management and protection
• File storage space management
• Directory management

5. OS and User Interface Management

Main Tasks:

Easy to use

Function:

User Interface (online user interface-command method, graphical user interface, offline User Interface)

Program Interface (system call)

7. Structure Design of the Operating System

The architecture design of the operating system has gone through the following generations:

Traditional Operating System Structure

• Unstructured Operating System
• Modular OS
• Hierarchical Structure OS

Customer/Server mode

Object-Oriented Programming

Microkernel OS STRUCTURE

Reference: China East University of Science and Technology Operating System
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