Operating Systems Lecture #1: Basic concepts of O/S Written by David Goodwin based on the lecture series of Dr. Dayou Li and the book Understanding Operating Systems 4thed. by I.M.Flynn and A.McIver McHoes (2006) Department of Computer Science and Technology, University of Bedfordshire. Operating Systems, 2013 28th January 2013 Outline Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire 1 Lectures Lectures Computer systems Concepts of O/S 2 Computer systems Types of O/S CPU structure 3 Concepts of O/S 4 Types of O/S 5 CPU structure Operating Systems 36 Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures 3 Computer systems Concepts of O/S Lectures Types of O/S CPU structure Operating Systems 36 Lecturing schedule Lecture #1 Basic concepts of O/S 1 Operating system concepts David Goodwin University of 2 Early paradigms of memory management Bedfordshire 3 Lectures 4 Modern memory management techniques Computer systems 4 I/O device management Concepts of O/S 5 File management Types of O/S CPU structure 6 Process management 7 Deadlock resolution 8 Critical sections 9 Concurrent processes 10 Security and ethics 11 Network organisation and management 12 Case Study: Memory management in real O/S 13 Case Study: Process management in real O/S 14 Revision Operating Systems 36 Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Computer systems 5 Concepts of O/S Computer systems Types of O/S CPU structure Operating Systems 36 O/S in computer systems Lecture #1 Basic concepts of O/S David Goodwin University of APPLICATIONS PROGRAMMES Bedfordshire Lectures Computer systems 6 SYSTEMS PROGRAMMES Concepts of O/S (Compilers, Assemblers, Linker etc.) Types of O/S CPU structure USER INTERFACE PROCESS MEMORY I/O FILE MANAGEMENT MANAGEMENT CONTROL MANAGEMENT Software Hardware CPU MAIN I/O SECONDARY MEMORY DEVICES STORAGE Operating Systems 36 O/S in computer systems Lecture #1 Basic concepts of O/S David Goodwin Hardware is the term used to describe all the physical University of Bedfordshire electronic and mechanical elements forming part of a computer system. Provides basic computing Lectures Computer systems 7 resources (CPU, memory, I/O devices) Concepts of O/S Software is the term used to describe the instructions or Types of O/S programs that the hardware needs in order to CPU structure function. Operating system controls and coordinates the use of the hardware among the various application programmes for various users Applications programmes define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programmes, etc.) Users (people, machines, other computers) Operating Systems 36 O/S in computer systems Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Computer systems 8 Concepts of O/S Types of O/S CPU structure Operating Systems 36 O/S in computer systems Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Computer systems 9 Concepts of O/S Resource allocator manages and allocates resources Types of O/S Control programme controls the execution of user programs and CPU structure operations of I/O devices Kernel the one programme running at all times (all else being application programmes) Operating Systems 36 Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Computer systems Concepts of O/S 10 Concepts of O/S Types of O/S CPU structure Operating Systems 36 Basic concepts of O/S Lecture #1 Basic concepts of O/S O/S definition David Goodwin O/S is a piece of software that controls every file, every University of Bedfordshire device, every section of main memory and every nanosecond Lectures processing time Computer systems Concepts of O/S 11 User interface Types of O/S CPU structure Processor Memory manager manager Device File manager manager Figure : Model of an operating system showing four sub-system managers supporting the user interface Operating Systems 36 Basic concepts of O/S Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Memory manager is in charge of main memory (RAM) in terms Computer systems Concepts of O/S 12 of checking validity of each request for memory Types of O/S space CPU structure Processor manager keeps track of status of each process Device manager monitors devices channels and contorl units and decides the most efficient way to allocate the devices File manager keeps track of every file Operating Systems 36 Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Computer systems Concepts of O/S Types of O/S Types of O/S 13 CPU structure Operating Systems 36 Types of O/S Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Computer systems O/S classification Concepts of O/S Types of O/S 14 Single user CPU structure Multiple tasks Batch systems Real-time systems Hybrid systems Embedded systems Operating Systems 36 Single user O/S Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Computer systems Provides capability to perform tasks on the computer system Concepts of O/S Types of O/S 15 such as writing programmes and documents, priniting and CPU structure accessing files Provides access to the computer system by a single user at a time, e.g. typical home computers Most Windows are single user operating systems Operating Systems 36 Multi-task O/S Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures A mutli-tasking operating system provides the ability to run Computer systems more than one programme at a time, e.g. word processing, Concepts of O/S printing a document, copying files to a flash memory stick. Types of O/S 16 Each of the tasks the user is performing appears to be CPU structure running at the same time. A multi-tasking operating system has the advantage of letting the user run more than one task at a time so as to increase productivity. The disadvantage is that the more programmes that are run by the user, the more memory that is required. Operating Systems 36 Multi-task O/S Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Manage and run all user requests, ensuring they do not Lectures interfere with each other, e.g. printer queue Computer systems Allow more than one user to access the computer system at a Concepts of O/S time, normally via a network, e.g. Unix 17 Types of O/S CPU structure Much more complex single-user operating system Operating Systems 36 O/S utilities Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures To manage the computer system, users, printers, files and Computer systems write programmes, the operating system is generally provided Concepts of O/S with a number of utility programmes. The utilities are used Types of O/S 18 for: CPU structure Managing files and documents Development of programmes and software Communicating between people and with other computer systems Managing user requirements for programmes, storage space and priority Operating Systems 36 O/S utilities Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures The operating system provides each user with an interface Computer systems that accepts, interprets and executes user commands or Concepts of O/S programmes Types of O/S 19 CPU structure This interface is commonly called a SHELL or Command Line Interpreter (CLI) In some systems this might be a simple text mode line-by-line entry using keywords (such as DOS or UNIX) In other systems it might be highly graphical using windows and pointing device such as a mouse (such as Windows) Operating Systems 36 Migration of O/S features Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Computer systems Concepts of O/S Types of O/S 20 CPU structure Operating Systems 36 Some O/S products Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Typical operating systems include: Lectures Unix/Linux Computer systems Windows 3.x/9x/NT/2000/XP/Vista/7 Concepts of O/S Mac OS Types of O/S 21 Windows Mobile CPU structure Symbian DOS VMS Operating Systems 36 Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Computer systems Concepts of O/S CPU structure Types of O/S CPU structure 22 Operating Systems 36 CPU structure Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire Lectures Computer systems Concepts of O/S Types of O/S A CPU consists of two sections CPU structure 23 1 Computational section 2 Control section Operating Systems 36 CPU structure Lecture #1 Basic concepts of O/S Computational section David Goodwin University of Structure Bedfordshire Lectures Computer systems Concepts of O/S Types of O/S memory CPU structure 24 Operating Systems 36 CPU structure Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire ALU (arithmetic logic unit) Performing arithmetic, shifting, logical AND, Lectures complementation, bypass operations Computer systems Datapath: Concepts of O/S Types of O/S Bus A and Bus B CPU structure 25 Registers ALU Bus C Control \tell" the ALU which operation to perform S: the sign bit of the output Z: bitwise NOT-OR of output (i.e. Z = 1 when all output bits are 0) Operating Systems 36 CPU structure Lecture #1 Basic concepts of O/S David Goodwin University of Bedfordshire ALU is the heart of a CPU Lectures It