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									         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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