Lecture 1 Introduction to Operating Systems History - Microsoft & Linux What Is an Operating System? An Operating System is the software that makes the computer's hardware usable. The OS manages the HW and the SW resources of the computer. An OS is a software application that is initiated upon computer startup and continues to run while the computer is operational. The purpose of an OS is to provide access to and control of application programs, file transfers and other tasks required by the computer user. The OS is the software that makes the computer hardware usable. End-User Applications Utilities Operating System Computer Hardware Why do we study Operating Systems? Because they are more interesting that the broken ones* To be able to manage our computer resources more effectively To take advantage of the functionality provided by the OS in our programming projects To build more secure software applications To better prepare us for the increasing complexity of networked and distributed software design and implementation * bahrumpbump Functions of an Operating System Separates applications from the hardware they access Software layer Manages software and hardware to produce desired results Operating systems primarily are resource managers Hardware Processors Memory Input/output devices Communication devices Software applications Mainframe Operating Systems History 1940’s No O.S. (The 0th Generation) all instructions handcoded in machine language one program resident in computer at a time programmer at console 1950’s Batch O.S. (The 1st Generation) batch processing - single jobs running to completion in sequence O.S. regains control after each job is completed programs included Job Control Language (JCL) to support O.S. functions 1960’s Multiprogramming O.S. (The 2nd Generation) multiprogramming - multiple jobs running concurrently on a mainframe device independence - peripherals interchangeable timesharine - interactive programming real-time systems - immediate response and hardware in the loop (HWIL) 1970’s Multimode O.S. (The 3rd Generation) multimode systems - combining batch, timeshare, real-time and multiprocessing software layer - layers of abstraction separating programmer and user from HW virtual machine - the emulation of one machine on another software became unbundled from hardware creating a new industry 1980’s Personal PC O.S. (The 4th Generation) personal computers - minicomputers, workstations, desktops, laptops, handheld local area network - regaining processing power by connecting smaller systems 1990’s Distributed O.S. (The 5th Generation) global interconnectivity - Internet, World Wide Web thin client - functionality left on server system to manage large databases Personal Computer Development Timeline 1974 Ed Roberts invents the ALTAIR 8800. Appears in Popular Electronics article. 1975 Paul Allen and Bill Gate create a BASIC Interpreter for the ALTAIR Allen and Gates take a paper tape copy of their BASIC Interperter to Roberts 1976 Allen and Gates move to Albequerque, NM and open an office across the street from Roberts’ company. This is the beginning of Microsoft. 1977 Steven Jobs and Steve Wozniak debut the Apple at the West Coast Computer Fair and sell 50 units. Jobs and Wozniak sell the first Apple II. Gary Kindall writes CP/M (Intergalactic Digital Research) sells 600,000 copies 1979 Steven Jobs tours Xerox Palo Alto Research Center and sees ethernet, laser printers, and a Graphical User Interface (GUI). 1980 IBM contacted Bill Gates looking for a BASIC interpeter and OS for their upcoming PC. 1980 Gates did not have an OS so he recommended that IBM talk to Kindall. Kindall was not available for the meeting but left his wife to talk with them. She would not sign their non-disclosure agreement so they gave up on getting CP/M. Apple sells 35,000 Apple II’s. Microsoft moves office to Bellevue, Washington Gates contacted Tim Patterson the creator of QDOS (an OS similar to CP/M). But Patterson would not make a deal since he had a exclusive rights agreement with a company called Seattle Computer Products. 1981 Microsoft goes ahead and makes a deal with IBM to provide BASIC and QDOS. Gates purchases the rights to QDOS from Seattle Computer Products for $50K and renames it PCDOS 1.0. Tim Patternson goes to work for Microsoft. 1982 Apple develops the Lisa (forerunner to the Macintosh). 1983 Microsoft recommends a GUI for DOS that would look-and-feel like the Mac OS but IBM rejects it. IBM asks Microsoft to help develop OS/2 to compete with clone operating systems 1984 Apple introduces the Macintosh during Superbowl. 1984 Microsoft breaks ties with IBM and begins work on Windows 1.0 Approximately 1000 servers connected to “Internet”. 1985 Microsoft releases Windows 1.0 1987 OS/2 are introduced and are largely ignored by the public. Microsoft announces Windows 2.0 Apple takes Microsoft to court and eventually loses. 1990 Microsoft introduces Windows 3.0 and sells over 30 million copies. 1992 Microsoft ships Windows 3.1 Apple’s Powerbook first computer to break $1 billion threshold 1994 Microsoft releases Windows 3.11 1995 Microsoft introduces Windows 95 and spends $300 million promoting it. 1999 Microsoft introduces Windows NT 5.0 Hardware Innovations that have Improved OS Performance Storage interleaving - making multiple banks of secondary storage independently accessible. Relocation register - holds address of program in memory so it made be moved during use. memory buffer - a block of memory used to hold data during I/O operations. I/O and DMA channels - special hardware to handle I/O and memory access instead of CPU cycle stealing - giving DMA channels priority access to memory over the CPU Interrupts vs polling - methods for peripherals to gain the attention of the CPU storage protection - limiting the range of programs in memory in a multiprogramming system clocks and timers - interval and real-time clocks are used to support job scheduling/sharing base-pluse-displacement - makes processes relocatable and permits shorter addresses virtual storage - allows the creation of arbitrarily large seamless programs multiprocessing - multiple processors sharing primary memory controlled by one OS pipelining - a technique to parallelize certain inherently sequential processes memory hierarchy - using different types of memory to improve performance, cache, RAM... Single-Platform Operating Systems The early OS's were designed to execute on a single computer. These systems had no mechanisms for accessing another computer through a network. Somewhat later in the history of OS's, tools were created for machine to machine data transfer through peer-to- peer connections, however these were limited to basic file transfer for copying and backup. Types of Operating Systems Real-Time OS - Features and settings not accessible by user. The primary goal of an RTOS is to ensure that a specific set of operations occur within a precise time period. Embedded OS - A single-user, single-tasking OS used on many small hand-held devices such as personal data assistants, cell-phones and media players. PC OS - These are the most popular and well-known type of OS, They are single-user, multi-tasking and are used on desktop and laptop computers. Mainframe OS - Also called a multi-user operating system, makes the resources of the computer simultaneously available to many different users. These OS must balance the processing load and resources to provide fair and effectice access to data and processes. Networked & Distributed OS - For many multi-user and client-server applications the mainframe computer has been replaced with many distributed computers managed by a single OS. Network Operating Systems A networking operating system is an operating system that contains components and programs that allow a computer on a network to serve requests from other computer for data and provide access to other resources such as printer and file systems. JUNOS, used in routers and switches from Juniper Networks. Cisco IOS (formerly "Cisco Internetwork Operating System") is a NOS having a focus on the internetworking capabilities of network devices. It is used on Cisco Systems routers and some network switches. BSD, also used in many network servers. Linux Microsoft Windows Server Novell Netware Distributed Operating Systems A distributed operating system is one that looks to its users like an ordinary centralized operating system but runs on multiple, independent central processing units (CPUs). The key concept here is transparency. In other words, the use of multiple processors should be invisible (transparent) to the user. Another way of expressing the same idea is to say that the user views the system as a virtual uniprocessor, not as a collection of distinct machines. - Tanenbaum Plan 9 from Bell Labs, a distributed operating system - designed from the ground up as a distributed system: the architecture of Plan 9 is inherently grid-enabled. Amoeba - an open source microkernel-based distributed operating system developed by Andrew S. Tanenbaum and others at the Vrije Universiteit. The aim of the Amoeba project is to build a timesharing system that makes an entire network of computers appear to the user as a single machine. (stalled) BOINC - Open-source software for volunteer computing and grid computing. Networked vs Distributed Operating Systems A typical configuration for a network operating system would be a collection of personal computers along with a common printer server and file server for archival storage, all tied together by a local network. Generally speaking, such a system will have most of the following characteristics that distinguish it from a distributed system: • Each computer has its own private operating system, instead of running part of a global, systemwide operating system. • Each user normally works on his or her own machine; using a different machine invariably requires some kind of “remote login,” instead of having the operating system dynamically allocate processes to CPUs. • Users are typically aware of where each of their files are kept and must move files between machines with explicit “file transfer” commands, instead of having file placement managed by the operating system. • The system has little or no fault tolerance; if 1 percent of the personal computers crash, 1 percent of the users are out of business, instead of everyone simply being able to continue normal work, albeit with 1 percent worse performance.
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