CSCI2413 Lecture 1 Operating Systems (OS) Introduction and Overview phones off (please)

© De Montfort University, 2004CSCI L12 Introduction Personal introduction Module outline Learning Plan, Weekly Topics Assessment Resources, Books, Web-Sites. Background Revision Architecture; general components Interrupt systems Addressing memory locations Representation of Data !?

© De Montfort University, 2004CSCI L13 Personal Introduction –Morteza Safavi RoomGH5.10 Tel

© De Montfort University, 2004CSCI L14 Overview of Computer Systems –Computer System Architecture and operation –Interrupts a DMA –Storage –Operating System definitions

© De Montfort University, 2004CSCI L15 Weekly Topics – Term 1 Week noLecture Title 1 Introduction and Overview 3 Operating System Overview 5 Concept of a “Process” 7 Process Management 9 Concurrency 11 Memory Management 1

© De Montfort University, 2004CSCI L16 Weekly Topics – Term 2 Week noLecture Title 16Memory Management 2 18Process Scheduling Techniques 20The IO management 22The File System 24File Management Techniques 29Security and Protection 30 Exam ??

© De Montfort University, 2004CSCI L17 Assessment Assessment by – Coursework: Phase test-1 10% (Thursday 16 th December,4.00 pm) Assignment (program or written report), 25%, Phase test-2 15% (Thursday 3 rd March,4.00 pm) –Exam50% time and date will be announced in good time

© De Montfort University, 2004CSCI L18 Resources Web Sites (linked from module home page) Books –Operating Systems 5th Edition – William Stallings – Prentice Hall, 2005 –Modern Operating Systems (2nd Ed.) – Andrew S Tanenbaum - Prentice Hall, 2001 –Operating Systems 4th Edition – Colin Ritchie – Continuum, 2003 –Operating Systems 3rd Edition – Nutt GJ Pearson 2004 –Structured Computer Organization - (4th Ed.) – Andrew S Tanenbaum - Prentice Hall, 1999

Overview of Computer Systems

© De Montfort University, 2004CSCI L110 Computer-System Architecture

© De Montfort University, 2004CSCI L111 Computer-System Operation I/O devices and the CPU can execute concurrently. Device controller is in charge of own device. Each device controller has a local buffer. CPU moves data from main memory to local buffers, or vice versa Device controller informs CPU of its operation by causing an interrupt.

© De Montfort University, 2004CSCI L112 Common Functions of Interrupts Interrupt transfers control to ISR, through the interrupt vector, which contains the addresses of all the service routines. Address of the interrupted instruction is saved on stack. Other interrupts are disabled An operating system is interrupt driven.

© De Montfort University, 2004CSCI L113 Interrupt Handling OS preserves the state of the CPU by storing registers and the program counter on stack. Determines which type of interrupt has occurred: –polling –vectored interrupt system Determine what action should be taken for each type of interrupt

© De Montfort University, 2004CSCI L114 Direct Memory Access Used for high-speed I/O devices able to transmit information at close to memory speeds. Device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention. Only one interrupt is generated per block, rather than the one interrupt per byte.

© De Montfort University, 2004CSCI L115 Storage Hierarchy Storage systems organized in hierarchy. –Speed –Cost –Volatility Caching – copying information into faster storage system; main memory can be viewed as a last cache for secondary storage.

© De Montfort University, 2004CSCI L116 Caching High-speed memory to hold recently-accessed data. Requires a cache management policy. Caching introduces another level in storage hierarchy. This requires data that is simultaneously stored in more than one level to be consistent

© De Montfort University, 2004CSCI L117 What is an Operating System? A program that acts as an intermediary between a user and the computer hardware. OS goals: –Execute user programs and make solving user problems easier. –Make the computer system convenient to use. Use the computer hardware in an efficient manner.

© De Montfort University, 2004CSCI L118 OS Definitions Resource allocator – manages and allocates resources. Control program – controls the execution of user programs and operations of I/O devices. Kernel – the one program running at all times (all else being application programs).

© De Montfort University, 2004CSCI L119 Summary Personal introduction Module outline –topics –assessment –resources the module web site Computer System Overview – Architecture and operation –Interrupts a DMA –Storage –Operating System definitions