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

2. 13 March 2003Operating Systems: Introduction2 Overview 1. Definition 2. Functions 3. Features 4. Developments 5. Products and Versions 6. User Interfaces

3. 13 March 2003Operating Systems: Introduction3 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. 13 March 2003Operating Systems: Introduction4 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. 13 March 2003Operating Systems: Introduction5 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. 13 March 2003Operating Systems: Introduction6 OS Features  Kernel  Controls hardware and rest of system  monolithic (everything) vs. microkernel (minimal)  File System  Command language and/or graphical user interface

7. 13 March 2003Operating Systems: Introduction7 Speed=Reducing Bottlenecks  Processor speed  Bus speed and width  Input/output devices  Memory transfer speed  Memory capacity  Storage devices  People (operators and users)

8. 13 March 2003Operating Systems: Introduction8 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. 13 March 2003Operating Systems: Introduction9 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. 13 March 2003Operating Systems: Introduction10 Operating Systems OSUsersTasksProcessors MS/PC DOSSS1 Windows 3xSQM1 Macintosh System 7.*SQM1 Windows 9xSM*1 AmigaDOSSM1 hline MTSMM1 UNIXMM VMSMM1 NTS/MM Windows 2000MM BeOS (Hamlet?)SM

11. 13 March 2003Operating Systems: Introduction11 Versions of UNIX UnixManufacturerMainly BSD/Sys 5 BSDBerkeleyBSD SunOS (solaris 1)Sun MicrosystemsBSD/sys 5 Solaris 2Sun MicrosystemsSys 5 UltrixDEC/CompaqBSD OSF 1/Digital UnixDEC/CompaqBSD/sys 5 HPUXHewlett-PackardSys 5 AIXIBMSys 5 / BSD IRIXSilicon GraphicsSys 5 GNU/LinuxPublic DomainPosix (Sys V/BSD) SCO unixNovellSys 5

12. 13 March 2003Operating Systems: Introduction12 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!