Introduction to Operating Systems

1
Introduction to Operating Systems

• Operating Systems
• Lecture 1, 13 March 2003
• Mr. Greg Vogl
• Uganda Martyrs University

2
Overview

1. Definition
2. Functions
3. Features
4. Developments
5. Products and Versions
6. User Interfaces

3
Operating System Definition

• The most important system software
• Controls internal functions of computer
• Interface between user and hardware
• Abstraction encapsulates (simplifies, hides) low
  level hardware details
• Hardware-software boundary is transparent to user

4
Functions of an OS

• Program management, process scheduling
• Memory management
• File and disk management
• Input/Output device control
• User interface
• User account and security management
• System software development tools
• Utilities

5
OS Files

• System programs
• Program loader, command interpreter
• Language processors
• Compiler, assembler, linker
• Utilities
• Text editors, terminal, backup/archive
• Subroutine libraries
• Standard C library, include files

6
OS Features

• Kernel
• Controls hardware and rest of system
• monolithic (everything) vs. microkernel
  (minimal)
• File System
• Command language and/or graphical user interface

7
SpeedReducing Bottlenecks

• Processor speed
• Bus speed and width
• Input/output devices
• Memory transfer speed
• Memory capacity
• Storage devices
• People (operators and users)

8
Historical Developments

• Bootstrapping (Booting)
• Loading the program that loads programs
• Batch processing
• Series of jobs sent to processor
• Spooling
• Jobs from slow I/O devices put in a queue on
  faster device for transfer to processor

9
Historical Developments

• Multiprogramming/multitasking
• Switching between running programs
• Multiprocessing
• More than one processor
• Multi-user time sharing
• Several users sharing access to a system
• Real time systems
• Must provide immediate response
• Influences, feedback from environment

10
Operating Systems
11
Versions of UNIX
12
Users

• Programmers
• Develop new system app. software
• Operators, System Administrators
• Manage and maintain systems, networks
• End Users
• Use application software
• Knowledge of OS is useful for all users!