[作業系統學習筆記]Operating System（二）

@Author：Y4tacker

文章目錄

• ​​Operating System(二)​​

• ​​operating System definition​​

• ​​other definition​​

• ​​Layers of Computer System​​
• ​​Services Provided by the Operating System​​
• ​​CPU mode​​

• ​​Kernel(核心)​​

• ​​Ease of Evolution of an Operating System​​
• ​​Processes​​

• ​​Some definition​​
• ​​Consists of three components​​

• ​​Memory Management​​

• ​​responsibilities​​
• ​​requirements​​

• ​​Virtual Memory / VM​​
• ​​Page​​

Operating System(二)

operating System definition

A program that controls the execution of application programs and acts as an interface between applications and hardware

other definition

• An operating system (OS) is an interface between hardware and user, which is responsible for the management and coordination of activities and the sharing of the resources of a computer, that acts as a host for computing applications run on the machine.
• One of the purposes of an operating system is to handle the resource allocation and access protection of the hardware. This relieves the application programmers from having to manage these details.

Layers of Computer System

Services Provided by the Operating System

• Program development

• Editors and debuggers

• Program execution

• loader

• Access to I/O devices
• Controlled access to files
• System access
• Error detection and response
• Accounting

CPU mode

• User program executes in user mode(使用者模式)

• Certain instructions may not be executed
• Some memory can not be accessed

• Monitor executes in system mode(系統模式) /Kernel mode(核心模式)

• Privileged instructions are executed
• Protected areas of memory may be accessed

Kernel(核心)

• Portion of operating system that is in main memory
• Contains most frequently used functions
• Also called the nucleus（核子）

Ease of Evolution of an Operating System

Serial Processing->Simple Batch Systems->Multiprogrammed Batch Systems->Time-Sharing Systems

。。。。。

As the content of the latter personal feeling is not necessary to record

Processes

Some definition

• A program in execution
• An instance(執行個體) of a program running on a computer
• The entity(實體) that can be assigned to and executed on a processor
• A unit of activity(活動機關) characterized by a single sequential thread of execution(單一的順序執行軌迹), a current state(目前狀态), and an associated set of system resources(系統資源)

Consists of three components

• An executable program /code
• Associated data needed by the program
• Execution context of the program (the core)

Memory Management

responsibilities

OS has five storage management responsibilities:

• Process isolation(程序隔離)
• Automatic allocation and management(自動配置設定和管理)
• Support of modular programming(子產品化程式設計)
• Protection and access control
• Long-term storage(長期存儲)

requirements

• Relocation/重定位
• Protection/保護
• Sharing/共享
• Logical organization /邏輯組織
• Physical organization /實體組織

Virtual Memory / VM

Page