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Introduction

Introduction. 1.1 What is an operating system 1.2 History of operating systems 1.3 The operating system zoo 1.4 Computer hardware review 1.5 Operating system concepts 1.6 System calls 1.7 Operating system structure. Chapter 1. Introduction. A computer system consists of hardware

kelly-williams
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Introduction

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  1. Introduction 1.1 What is an operating system 1.2 History of operating systems 1.3 The operating system zoo 1.4 Computer hardware review 1.5 Operating system concepts 1.6 System calls 1.7 Operating system structure Chapter 1

  2. Introduction • A computer system consists of • hardware • system programs • application programs

  3. What is an Operating System • It is an extended machine • Hides the messy details which must be performed • Presents user with a virtual machine, easier to use • It is a resource manager • Each program gets time with the resource • Each program gets space on the resource

  4. History of Operating Systems (1) • First generation 1945 - 1955 • vacuum tubes, plug boards • Second generation 1955 - 1965 • transistors, batch systems • Third generation 1965 – 1980 • ICs and multiprogramming • Fourth generation 1980 – present • personal computers

  5. History of Operating Systems (2) Early batch system • bring cards to 1401 • read cards to tape • put tape on 7094 which does computing • put tape on 1401 which prints output

  6. History of Operating Systems (3) • Structure of a typical FMS job – 2nd generation

  7. History of Operating Systems (4) • Multiprogramming system • three jobs in memory – 3rd generation

  8. The Operating System Zoo • Mainframe operating systems • Server operating systems • Multiprocessor operating systems • Personal computer operating systems • Real-time operating systems • Embedded operating systems • Smart card operating systems

  9. Computer Hardware Review (1) Monitor • Components of a simple personal computer Bus

  10. Computer Hardware Review (2) (a) A three-stage pipeline (b) A superscalar CPU

  11. Computer Hardware Review (3) • Typical memory hierarchy • numbers shown are rough approximations

  12. Computer Hardware Review (4) Structure of a disk drive

  13. Computer Hardware Review (5) One base-limit pair and two base-limit pairs

  14. Computer Hardware Review (6) (a) Steps in starting an I/O device and getting interrupt (b) How the CPU is interrupted (a) (b)

  15. Computer Hardware Review (7) Structure of a large Pentium system

  16. Operating System Concepts (1) - Processes • A process is a program in execution • Swapping of a process – Process table entry • System calls to create and terminate processes • System calls to allocate/deallocate memory • System calls for communication - signals

  17. Operating System Concepts (2) - Processes • A process tree • A created two child processes, B and C • B created three child processes, D, E, and F

  18. Operating System Concepts (3) -Deadlocks (a) A potential deadlock. (b) an actual deadlock.

  19. Operating System Concepts (4) - Files • Present the programmer with nice, clean, abstract, device-independent files. • Concept of directory to group files together • System calls to create/remove directories and create/remove files. Hierarchies. • Process trees != Directories • A file can be specified by a path name: absolute (from root), relative (from current working directory).

  20. Operating System Concepts (5) - Files File system for a university department

  21. Operating System Concepts (6) - Files • Protection of files and directories, e.g. UNIX the rwx bits: 9 bits (owner/group/others) rwxr-xr-- • File Descriptor: a number assigned to a file. • Mounting file systems. • Special files: block special files, character special files – standard input (fd=0), standard output (fd=1), standard error (fd=2).

  22. Operating System Concepts (7) - Files • Before mounting, • files on floppy are inaccessible • After mounting floppy on b, • files on floppy are part of file hierarchy

  23. Operating System Concepts (8) - Pipes Two processes connected by a pipe. Read/Write - transparent for processes.

  24. Operating System Concepts (8) - Shell • The shell is a program that acts as an interface between the user and the OS. • Unix: several shells (e.g. csh, ksh). • MSDOS: command prompt. • Prompt, process, std input, output, creates processes.

  25. Steps in Making a System Call There are 11 steps in making the system call read (fd, buffer, nbytes)

  26. Some System Calls For Process Management

  27. Some System Calls For File Management

  28. Some System Calls For Directory Management

  29. Some System Calls For Miscellaneous Tasks

  30. System Calls (1) • A stripped down shell: while (TRUE) { /* repeat forever */ type_prompt( ); /* display prompt */ read_command (command, parameters) /* input from terminal */ if (fork() != 0) { /* fork off child process */ /* Parent code */ waitpid( -1, &status, 0); /* wait for child to exit */ } else { /* Child code */ execve (command, parameters, 0); /* execute command */ } }

  31. System Calls (2) • Processes have three segments: text, data, stack

  32. System Calls (3) (a) Two directories before linking/usr/jim/memo to ast's directory (b) The same directories after linking

  33. System Calls (4) (a) File system before the mount (b) File system after the mount

  34. System Calls (5) Some Win32 API calls

  35. Operating System Structure • Monolithic • Layered • Virtual Machines • Client-Server

  36. Operating System Structure (1) User program 1 User program 2 Kernel call 4 1 Service procedure 3 2 dispatch table

  37. Operating System Structure (1) Simple structuring model for a monolithic system

  38. Operating System Structure (2) Structure of the THE operating system

  39. Operating System Structure (3) Structure of VM/370 with CMS

  40. Operating System Structure (4) The client-server model

  41. Operating System Structure (5) The client-server model in a distributed system

  42. Metric Units The metric prefixes

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