Embed Size (px)
Citation preview
An Operating SystemHistory of Operating Systems
Operating Systems
P. Healy
CS1-08Computer Science Bldg.
tel: [email protected]
Autumn 2019–2020
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 1 / 27
An Operating SystemHistory of Operating Systems
Outline
1 An Operating System
2 History of Operating SystemsEarly HistoryEarly 21st CenturyUNIX and its variants
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 2 / 27
An Operating SystemHistory of Operating Systems
What is an Operating System?
From the user’s point of view an OS is:A program that acts as an intermediary between a user ofa computer and the computer hardwareControls and coordinates use of hardware amongapplications and usersOperating system goals:
Execute user programs and make solving user problemseasier
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 3 / 27
An Operating SystemHistory of Operating Systems
Four Levels of a Computer System
User 1 Process 2 · · · User m Process n
System and User Applications
Operating System
Computer Hardware
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 4 / 27
An Operating SystemHistory of Operating Systems
Four Levels of a Computer System
User 1 Process 2 · · · User m Process n
System and User Applications
Operating System
Computer Hardware
System and User Applications: Application programs definethe ways in which the system resources are used to solve thecomputing problems of the users: word processors, compilers,web browsers, database systems, games
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 4 / 27
An Operating SystemHistory of Operating Systems
Four Levels of a Computer System
User 1 Process 2 · · · User m Process n
System and User Applications
Operating System
Computer Hardware
Operating System: Controls and coordinates use of hardwareamong various applications and users
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 4 / 27
An Operating SystemHistory of Operating Systems
Four Levels of a Computer System
User 1 Process 2 · · · User m Process n
System and User Applications
Operating System
Computer Hardware
Computer Hardware: Provides basic computing resourcessuch as CPU, memory, I/O devices
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 4 / 27
An Operating SystemHistory of Operating Systems
Four Levels of a Computer System (contd.)
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 5 / 27
An Operating SystemHistory of Operating Systems
Technical Point of View
OS is a resource allocatorManages all resourcesDecides between conflicting requests for efficient and fairresource use
OS is a control programControls execution of programs to prevent errors andimproper use of the computer
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 6 / 27
An Operating SystemHistory of Operating Systems
Another Point of View
No universally accepted definition“Everything a vendor ships when you order an operatingsystem” is good approximation“The one program running at all times on the computer” isthe kernel of the OS; everything else is either a systemprogram (ships with the operating system) or anapplication program (e.g., a browser, or a paint program)
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 7 / 27
An Operating SystemHistory of Operating Systems
What an OS is not
An operating system is different from the (graphical)interface through which we interactAlthough on Windows there tends to be just one graphicalinterface other OSs (e.g. Linux) have several differentinterfacesThe interface may change but the OS remains the same
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 8 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
Outline
1 An Operating System
2 History of Operating SystemsEarly HistoryEarly 21st CenturyUNIX and its variants
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 9 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
The 1940s and 1950s
Operating systems evolved through several phases.1940s:
Early computers did not include operating systems1950s:
Executed one job at a timeSingle-stream batch-processing systemsIncluded technologies to smooth job-to-job transitionsPrograms and data submitted consecutively on tape
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 10 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
The 1960s
Batch-processing systems still in useTurnaround time (the time it takes to receive finishedreports after submission of documents or files forprocessing ) was reduced to minutes or secondsMultiprogramming: Process multiple jobs at once; onejob could use processor while other jobs used peripheraldevicesTimesharing: Advanced operating systems developed toservice multiple interactive usersReal-time systems: response within certain bounded timeperiodIn 1964 IBM announced System/360 family of mainframecomputers
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 11 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
The 1960s (contd.)
CTSS (Compatible Time-Sharing System) was one of thefirst time-sharing operating systems; it was developed atMIT’s Computation Center
CTSS was first demonstrated in 1961, and was operated atMIT until 1973CTSS used a modified IBM 7094 mainframe computerLouis Pouzin created a command called RUNCOM forCTSS, which executed a list of commands contained in afile (batch file)
1964: MIT, GE, Bell Labs started the MULTICS(Multiplexed Information & Computing Service) project
MULTICS was a commercial OS based on CTSSLast working copy was shut down on 31 Oct 2000
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 12 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
The 1970s
Primarily multimode timesharing systems:Supported batch processing, timesharing and real-timeapplicationsPersonal computing only in incipient stages fostered byearly developments in microprocessor technology (XeroxAlto)Mouse and Graphical user interfaces (GUI) developed byXerox’s PARC for the Xerox Alto computer
NetworkingThe US Department of Defense develops TCP/IP:
Standard communications protocolWidely used in military and university settings
Xerox’s Palo Alto Research Centre (PARC) – EthernetSecurity problems: Growing volumes of information passedover vulnerable communications lines −→ Encryption
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 13 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
The 1980s
Decade of personal computers and workstationsComputing distributed to sites at which it was neededIBM PC released in 1981Personal computers proved relatively easy to learn and useApple releases the Macintosh PC in 1984, GUI embeddedin the operating systemRichard Stallman launched the GNU (GNU’s Not UNIX)project in 1983:
Recreate and extend tools for AT&T’s UNIX operatingsystemHe disagreed with concept of paying for permission to usesoftware
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 14 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
The 1980s (contd.)
Transferring information between computers via networksbecame more economical and practicalClient/server computing model became widespread:
Clients request various servicesServers perform requested services
Software engineering field continued to evolveMajor thrust by the United States government aimed attighter control of Department of Defense software projects
Realizing code reusabilityGreater degree of abstraction in programming languagesMultiple threads of instructions that could executeindependently
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 15 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
The 1990s
Hardware performance improving exponentially1:Inexpensive processing power and storage
Execute large, complex programs on personal computersEconomical machines for extensive database andprocessing jobsMainframes rarely necessary
Operating system support for networking tasks becamestandardShift toward distributed computing rapidly accelerated:multiple independent computers performing common task
1Moore’s “Law”: number of transistors on a computer chip (a proxy forcomputing speed??) doubles every 18 months
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 16 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
The 1990s (contd.)
Object technology became popular in many areas ofcomputing:
Many applications written in object-oriented programminglanguages (C++, Java)Object-oriented operating systems (OOOS): objectsrepresent components of the operating systemConcepts such as inheritance and interfaces:
Exploited to create modular operating systemsEasier to maintain and extend than systems built withprevious techniques
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 17 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
The 1990s (contd.)
Most commercial software sold as object code:The source code not includedEnables vendors to hide proprietary information andprogramming techniques
Free and open-source software became increasinglycommon in the 1990s:
Allows individuals to examine and modify softwareFamous example: In 1991, a student in Finland, LinusTorvalds, released a rudimentary UNIX-like kernel using theGNU compilers and tools and invited contributionsworldwide
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 18 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
The 1990s (contd.)
Accessing OSs became increasingly user-friendly:GUI features pioneered by Xerox and Apple widely usedand improved“Plug-and-play” capabilities built into operating systems:
Enable users to add and remove hardware componentsdynamicallyNo need to manually reconfigure operating system
Microsoft Corporation became dominant:Windows operating systems (Windows 3.0 released in1990)
Employed many concepts used in early MacOS
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 19 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
Outline
1 An Operating System
2 History of Operating SystemsEarly HistoryEarly 21st CenturyUNIX and its variants
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 20 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
Cloud Computing
YouTube Video #1YouTube Video #2
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 21 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
Outline
1 An Operating System
2 History of Operating SystemsEarly HistoryEarly 21st CenturyUNIX and its variants
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 22 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
History
1964 - 69: MULTICS (Bell Labs, General Electric, MIT):All things to all peopleLarge, expensive and complex
1969: Bell Labs withdrew from the MULTICS projectA small team led by Ken Thompson began designing amore practical OS for the Bell Labs’ machines
First name: UNICS – a play on the “multi” aspect ofMULTICSSpelling evolved to UNIX
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 23 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
History (contd.)
Over the next few years UNIX was rewritten in Thompson’sB language and then in Denis Ritchie’s C languageAT&T was not allowed to sell UNIX
UNIX’s source code was distributed to universities for asmall fee
A group at the University of California at Berkeley modifiedthe UNIX source code to create the Berkeley SOFTWAREDistribution UNIX (BSD UNIX)
Led by Bill Joy, a co-founder of Sun Microsystems
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 24 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
History (contd.)
Sun Microsystems based their SunOS on BSD UNIXLater teamed up with AT&T to design Solaris, based onAT&T’s System V Release 4 UNIXAs an opposition to the AT&T and Sun Microsystemsassociation, a group of developers formed the OpenSource Foundation (OSF) to make their own version ofUNIX called OSF/1
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 25 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
UNIX and Linux
In 1987, Prof. Andrew Tanenbaum from the Vrije Universityin Amsterdam built Minix
A stripped-down version of UNIX for teaching OS basics ona PC.
Linus Torvalds, a Finish student, used Minix to beginwriting the open-source Linux OSToday many companies incl. IBM, HP, and Intel all offer aLinux version as an operating system option for theirserversOther UNIX clones include: OpenBSD, FreeBSD, Net-BSD,IBM’s AIX based on both System V and BSD, HP-UX (astrong competitor to Aix and Solaris)
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 26 / 27
An Operating SystemHistory of Operating Systems
Early HistoryEarly 21st CenturyUNIX and its variants
History (contd.)
P. Healy (University of Limerick) CS4023 Autumn 2019–2020 27 / 27
