Ceng 305 Operating Systems Overview

Operating Systems Course Information

• Course name: Ceng 305
• Instructor: İhsan Tolga Medeni, PhD
• Department: MIS, Ankara Yildirim Beyazit University
• Email: [email protected]
• Textbook: Modern Operating Systems, 4th Edition, by Andrew S. Tanenbaum and Herbert Bos
• Teaching Assistant (TA): Hatice Çataloluk

Course Content

• Course information (personnel, policies, prerequisites, agenda)
• Why learn operating systems?
• What is an operating system? What does it do?
• Operating System Goals
  • Understand operating system concepts
  • Understand how operating systems work, and why
  • Set a foundation for future learning
• Course Content Overview
  • Computer hardware overview
  • Threads and processes
  • Synchronization and concurrency
  • Scheduling
  • Memory management (virtual memory)
  • Disk management and file systems
  • Advanced topics

Prerequisites

• Programming experience in C and Java
• Computer organization concepts
  • Instructions (e.g., load, store)
  • CPU (Central Processing Unit)
  • Memory
  • Registers
  • Stack and stack pointer
  • Program counter (PC)

Grading

• Exams:
  • Midterm: 30%
  • Final: 40%
• Assignments/Quizzes: 30%
• No extensions for deadlines

Exams

• Midterm covers the first half of the course
• Final covers the entire semester

Cheating Policy

• Zero tolerance for academic dishonesty
• Cheating, aiding cheating, and any form of academic dishonesty will result in a failing grade for all parties involved

Why Learn Operating Systems?

• To pass the course and earn a graduate degree
• Operating systems are fundamental to all applications
• Software engineers need to understand them
• Companies value graduates with this knowledge: Microsoft, Apple, VMware, Google

What is an Operating System (OS)?

• OS Concepts
  • How OS functions regarding elevators? (Embedded OS)
  • How OS functions regarding satellites? (Real-time OS)
  • How OS functions regarding mobile phones? (Mobile OS, power consumption)
  • How OS functions regarding personal computers? (Multitasking, responsiveness)
  • How OS functions regarding computer servers? (Multi-user support, resource utilization).

Computer Organization

• Detailed diagram of computer architecture showing components and connections

I/O Structure

• After I/O starts, control returns to user program only upon I/O completion
• Wait instructions idle the CPU until the next interrupt
• At most one I/O request is outstanding at a time

Storage Structure

• Main memory is the only storage media the CPU can directly access
• Secondary storage extends main memory, providing large, non-volatile capacity
• Magnetic disks are used for storage
  • Logical divisions in tracks, then sectors

Process Management

• Activities
  • Creating and deleting processes (user and system)
  • Suspending and resuming processes
  • Mechanisms for process synchronization
  • Mechanisms for process communication
  • Mechanisms for deadlock handling

Memory Management

• All data in memory before and after processing
• Instructions remain in memory during execution
• Memory management decides what, where, and when is in memory
• Activities include tracking which parts are in use, moving processes and data in and out of memory, and allocating/deallocating memory space as needed

Storage Management

• OS provides a uniform, logical view of information storage
• Abstracts physical properties into logical storage units (files)
• Each storage device (e.g., disk drive, tape drive) is controlled individually
• File system management includes creating/deleting files and directories, file/directory manipulation primitives, mapping onto secondary storage, archival (backup) onto stable storage

Command-Line Interfaces (CLIs)

• Allow direct command entry
• Sometimes implemented in kernel, sometimes by system programs
• Can be composed of built-in commands or names of programs
• Adding new features to commands does not require shell modification

Graphical User Interfaces (GUIs)

• Desktop metaphor use mouse, keyboard, monitor
• Icons represent data, programs, and actions
• Various mouse operations (buttons) on GUI objects trigger actions
• Invented at Xerox PARC

System Calls

• Programming interface to OS services
• Typically written in high-level languages (C or C++)
• Accessed by programs via Application Programming Interfaces (APIs)

API-System Call-OS Relationship

• Diagram showing relationships between user applications, user mode, kernel mode, and system call interface

History of Operating Systems

• Early eras included batch systems, multiprogramming, and the rise of PCs
  • The Dark Age (1945-55)
  • Batch Systems (1955-65)
  • Multiprogramming (1965-80)
• Key Operating Systems like IBM's MS-DOS, UNIX, and Linux

OS Structures

• Simple structure (e.g., MS-DOS): not divided into modules, interfaces and levels not well-separated
• Layered approach: OS divided into multiple layers (0 for hardware up to N for user interface)
• Microkernel structure: more modules, in user space, use message passing between modules
• Mac OS-X structure: kernel modules, object orientation approach, talks to each other over interfaces, can be loaded/unloaded as needed