CS 444 Introduction to Operating Systems

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CS 444Introduction to Operating Systems

• Lecturer Dr. Ronald Cheung
• Office S/3/073
• Phone [phone]
• Email cheungr_at_cs.umb.edu

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Course Objectives

• This course will teach you details of the
  operating system
• It will cover topics
• Processes and threads
• Deadlocks
• Memory management
• I/O systems
• File systems
• Real-time operating systems

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Introduction

• Fill out the Class Information Sheet
• Syllabus and Lecture Notes
• Web http//www.cs.umb.edu/cheungr/cs444
• Required Textbooks
• Modern Operating Systems, 3rd Ed., A. Tanenbaum

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Introduction

• HW assignments
• Assignment write-ups will be on my website
• HW will be done from the ulab UNIX machine and
  downloaded to the SAPCs
• All HW will be done remotely
• Homework is an Individual Effort
• You can answer questions for each other as long
  as you acknowledge any help that you receive from
  others
• BUT DONT HAVE OR LET ANYONE ELSE DO YOUR
  HOMEWORK FOR YOU!
• If I discover any cheating, Ill follow school
  policy!

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Getting Started

• UNIX Account
• Apply for a CS444 account on the ulab machine
  ASAP!
• Edit your .cshrc file to add load module ulab
• Set up environment to compile programs that can
  run on SAPCs
• Use Sun Blades in UNIX Lab (S-3-157)
• Use rlogin ulab to access SAPCs
• Remote access from your home
• Connect to and login on ulab.cs.umb.edu
  directly
• Must use Secure Shell 2(ssh2) for remote access

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Getting Started

• Putty (Officially Recommended by Systems Staff)
• http//www.chiark.greenend.org.uk/sgtatham/putty/
  
• Download, UnZIP and Execute Installer as directed
• Use Putty configured for SSH2 instead of TELNET
• Use PSCP or PSFTP for secure ftp
• SSH Communications (Recommended by me)
• Information http//www.ssh.com/products/
• Download ftp//ftp.ssh.com/pub/ssh/SSHSecureShel
  lClient-3.2.9.exe
• Download and Execute Installer as directed

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Getting Started

• Four windows
• Window to local file folder for your source files
• Notepad to edit/save a text source file locally
• SSH Secure File Transfer to transfer the locally
  stored source file to the UNIX system
• SSH Secure Shell to run UNIX commands
• You are on your own to try this on your own PC!
• Dont send problem reports to operator for help!

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Getting Started

• Assume students know C programming, make, and
  tools such as mtip, Tutor, gdb from ulab
• Useful links on ulab
• http//www.cs.umb.edu/ulab
• Professor Wilsons CS 341 lectures
  www.cs.umb.edu/bobw/CS341

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Components of a Computer System

• Operating system runs in kernel (supervisory)
  mode
• Protected from user tempering by hardware
• Other software runs in user mode
• users are free to modify if he/she so chooses

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What is an Operating System?

• Programming at machine language level primitive
  and awkward
• Operating System provides a virtual machine (VM)
  that is easier to program
• A collection of services that applications can
  invoke using system calls
• Some OS VM (e.g. Java) sits on top of the OS VM

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A Bottom-up View

• OS manages all pieces of a complex system
• Provides an orderly and controlled allocation and
  access of hardware resources
• Arbitrates which application has access to what
  resources at what time

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Categories of Operating Systems

• Server OS (UNIX, Windows 2000, Linux)
• serves multiple users
• PC OS (Mac OS, Windows 98)
• serves a single user
• Real-time OS (VxWorks, pSOS)
• completes tasks within a given time budget
• Embedded OS (PalmOS, Windows CE)
• fits into small hand held device

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UNIX/Win32 Virtual Machine

• Time sharing each application uses CPU as if it
  owns it
• Private flat memory
• Stack that grows automatically when items are
  pushed on it
• System calls - functions called by application to
  do I/O, etc.

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User Memory Layout
Important powers of 2 1G230, 1M220,
1K210 0xFFFFFFFF 232 -1 4G-1
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Dynamic Link Library(DLL)

• Also known as dynamic library
• code can be called by a program that is not
  stored in the programs executable file
• brought to memory at runtime via dynamic linkage
  to users program
• calls to library are direct since it is in user
  memory

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Example of UNIX System Calls

• See debugging session captured in syscalls.html
• C program runs on a Sun Sparc machine with the
  Solaris OS