[Chapter2] Operating System Structure

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Operation-System Services

• user interface, program execution, I/O operation, file system manipulation, Communication, error detection, resource allocation, logging, protection/security

User and operation-System interface

• Command-Interpreter
• Graphical User Interface
• Touch-Screen Interface
• Choice of Interface

System Calls

• Application Programming Interface
  • ex) Windows API, POSIX API, Java API
• Types of System Calls

System Services

Linkers and Loaders

Why Applications Are Operating-System Specific

Operating-System Design and Implementation

• Design goals
• Mechanisms and Policies
• Implementation

Operation-System Structure

• Monolithic Structure
• Layered Approach
• Microkernels
• Modules
• Hybrid Systems

Building and Booting an Operating System

• Operating-System Generation
• System Boot

Operating-System Debugginng

• Failure Analysis
• Performance Monitoring and Tuning
• Tracing
• BCC

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❔ What is the purpose of Systems call

In general, system calls are required in the following situations

• If a file system requires the creation or deletion of files. Reading and writing from files also require a system call.
• Creation and management of new process.
• Newwork connections also requires system call. This includes sending and receiving packets
• Access to a hardware device such as a printer, scanner etc. requires a system call.

Types of System calls

• Process Control
• File Management
• Device Management
• Information Maintenance
• Communication

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❔ What is the purpose of command interpreter?

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❔ What is the purpose of System programs?

The system program serves as a part of the operating system. It traditionally lies between the user interface and the system calls.

In the above images, system programs as well as application programs form a bridge between the user interface and the ysstem.

Types of System Programs

• Status Information
  • System date, system time, available memory in system, disk space, logged in users etc.
• Communications
  • create files, delete files, copy the contents of one file into another, rename files, print them etc
• File Manipulation
• Program Loading and Execution
  • Loaders, Linkers
• File Modification
  • text editors
• Application Programs
  • database systems, word processors, plotting tools, spreadsheets, games, scientific application etc.
• Programming Language Support
  • compilers, debuggers

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❔ What is the main advantage of the layered approach to system design ?

Advantages

• Modularity
• Easy debugging
• Easy update
• No direct access to hardware
• Abstraction

Disadvantages

• Complex and careful implementation.
• Slower in execution

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❔ what are operation services?

The services offered by the operating system are as follows

• Input/Out put operation
• Resource allocation
• File System manipulation
• User interface
• Program execution
• Communication
• Security

The two main roles of the operation system are

• Resource Management
• Security

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❔ Difference between Firmware and Operating System

No	Firmware	Operating System
1	It's piece of programming code embedded in a particular hardware	Is is system software that operates as the foundation layer on a computer
2	It resides in ROM	It resides on a disk.
3	It is a small program	It is a huge progam
4	It is usually fixed.	It is often updated on a regular basis.
5	It is a low-level operation	It is a high-level interface
6	It has a single purpuse.	It is a general-purpose system that allows and kind of software to run on multiple types of hardware.
7	It resides in keyboards, video cards, routers, webcams, motherboards, mice, microwave ovens, refrigerators, washing machines, etc	Examples - Apple macOS, Microsoft windows, Google's android OS, Linux Operating System, and Apple IOS.