Time-Sharing - Israel Institute of Technologygotsman/236801/4-Time-Sharing.pdf · 2 Seminar in computer History CS236801 7 Why Time-Sharing is good Finance • Sharing devices –

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Seminar in computer History CS236801Seminar in computer History CS236801 11

TimeTime--SharingSharing


IntroductionIntroduction

•• OriginOrigin•• Why TimeWhy Time--Sharing is goodSharing is good•• Batch VS TimeBatch VS Time--SharingSharing•• Sun TechnologiesSun Technologies•• MIT CTSS SystemMIT CTSS System•• Operating systemsOperating systems•• TeletypeTeletype•• 11stst computers developed for TScomputers developed for TS


Origin Origin -- Claim to the TermClaim to the Term

•• ““Time SharingTime Sharing”” or or ““TimeTime--SharingSharing”” (1957(1957--1966)1966)•• Who invented the term : Who invented the term : ““TimeTime--SharingSharing”” ??


Why TimeWhy Time--Sharing is goodSharing is good

•• Most of the time the CPU is idleMost of the time the CPU is idle•• Waiting for input/outputWaiting for input/output


TimeTime--SharingSharing

•• TimeTime--sharingsharing refers to sharing a computing refers to sharing a computing resources among many users by resources among many users by multitaskingmultitasking

•• Hardware only design to support the TS while Hardware only design to support the TS while software is responsible to all TSsoftware is responsible to all TS

•• Lots of users at the same timeLots of users at the same time


MultitaskingMultitasking

•• Multiple tasks, also known as Multiple tasks, also known as processesprocesses, , share common processing resources such share common processing resources such as a as a CPUCPU

•• Illusion of Illusion of parallelismparallelism is achieved is achieved

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Why TimeWhy Time--Sharing is goodSharing is goodFinanceFinance

•• Sharing devices Sharing devices –– one main computers and the rest one main computers and the rest are terminalsare terminals

•• Saves CPU unused time while waiting for others I/OSaves CPU unused time while waiting for others I/O


Batch vs. TimeBatch vs. Time--SharingSharing

•• BatchBatch Advantage Advantage --•• Efficient for ensuring that computer not sitting idleEfficient for ensuring that computer not sitting idle•• Jobs can run unsupervisedJobs can run unsupervised



•• BatchBatch Disadvantage Disadvantage ––•• Takes hours/overnight to see resultsTakes hours/overnight to see results•• Not interactiveNot interactive•• Single user at the same timeSingle user at the same time•• CPU can be idle most of the timeCPU can be idle most of the time



•• TimeTime--SharingSharingAdvantage Advantage ––•• Work directly with the computer Work directly with the computer

and see results immediatelyand see results immediately•• CPU is used most of the timeCPU is used most of the time



•• TimeTime--SharingSharingDisadvantagesDisadvantages•• Much more expensive to Much more expensive to developedevelope•• Hard to implementHard to implement•• New hardwareNew hardware


Sun MicrosystemsSun Microsystems

•• Unix's influence in academic circles led to Unix's influence in academic circles led to largelarge--scale adoption of Unix by scale adoption of Unix by commercial startups, the most notable of commercial startups, the most notable of which is which is Sun MicrosystemsSun Microsystems. .

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Sun MicrosystemsSun Microsystems

•• Bill JoyBill Joy studied at Berkeley, released the studied at Berkeley, released the first free version of UNIX (1978) operating first free version of UNIX (1978) operating system which is now known as system which is now known as BSD UNIXBSD UNIX

•• Later he coLater he co--founded founded Sun MicrosystemsSun Microsystemsin 1982in 1982


•• The first generation of The first generation of UNIXUNIX computer computer workstationsworkstations and and serversservers produced by Sunproduced by Sun

•• Less than 200 SunLess than 200 Sun--1 systems were sold1 systems were sold•• The CPU board used a 10 MHz The CPU board used a 10 MHz •• Had 256 KB of Had 256 KB of RAMRAM, (Max 4MB), (Max 4MB)

Sun Sun -- 11


•• Had a 10 MHz which enabled it to be the first Had a 10 MHz which enabled it to be the first Sun architecture to run a full Sun architecture to run a full virtual memoryvirtual memoryUNIX implementation, UNIX implementation, SunOSSunOS 1.01.0

•• 8MB of physical and 16MB of virtual memory 8MB of physical and 16MB of virtual memory

Sun Sun -- 22


Sun386iSun386i

•• An An Intel 80386Intel 80386--based machine based machine •• Was designed to be a hybrid system, running Was designed to be a hybrid system, running

SunOS but at the same time supporting DOS SunOS but at the same time supporting DOS applicationsapplications

•• A followA follow--up "486i" up "486i" -- a few prototype units a few prototype units were ever manufactured were ever manufactured


Sun WorkstationsSun Workstations

•• Sun was predominantly a vendor of Sun was predominantly a vendor of technical technical workstationsworkstations, competing , competing successfully as a lowsuccessfully as a low--cost vendor during cost vendor during the Workstation Wars of the 1980s the Workstation Wars of the 1980s

•• In 1987 Sun takes lead in workstation In 1987 Sun takes lead in workstation market market


Sun SPARCSun SPARC

•• SPARCstation 1 system introducedSPARCstation 1 system introduced. . Features Features are so tightly integrated it fits in a 3are so tightly integrated it fits in a 3--1616--1616--inch inch enclosureenclosure -- the first the first ""pizza boxpizza box." ."

•• In 1990 In 1990 -- new models including the first new models including the first workstation for under $5,000workstation for under $5,000

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The MIT CTSS SystemThe MIT CTSS System

•• CTSS CTSS -- CCompatible ompatible TTimeime--SSharing haring SSystemystemDeveloped at Developed at MITMIT's Computation Center 's Computation Center

•• Was one of the first Was one of the first timetime--sharingsharing operating systemsoperating systems•• Operated at MIT until 1973 Operated at MIT until 1973


The MIT CTSS SystemThe MIT CTSS System

•• Designed for IBMDesigned for IBM--70907090’’s computer (mainly 7094)s computer (mainly 7094)•• In 1963 came IBM 7750 In 1963 came IBM 7750 –– capable of supporting capable of supporting

up to 112 up to 112 teleprinterteleprinter terminals terminals


The MIT CTSS SystemThe MIT CTSS SystemThe AlgorithmThe Algorithm

•• Find next task with highest priorityFind next task with highest priority•• Task that donTask that don’’t ran for 60 sec. gets higher t ran for 60 sec. gets higher

prioritypriority•• In level q, run task for till I/O occur or 0.5*2In level q, run task for till I/O occur or 0.5*2qq

(max is 128 Sec)(max is 128 Sec)•• Schedule next taskSchedule next task


The MIT CTSS SystemThe MIT CTSS SystemThe AlgorithmThe Algorithm

•• IMPORTANT IMPORTANT --•• Have you seen the Have you seen the similaritysimilarity between between

nowadays scheduler and 50 before ?nowadays scheduler and 50 before ?

•• Right !!! Right !!! The same concepts The same concepts Little more sophisticatedLittle more sophisticated


TopsTops--1010

•• Had an interesting Had an interesting schedulerscheduler with many run with many run queues.queues.

•• Very fast and flexible Very fast and flexible operating system that was operating system that was far ahead of its time far ahead of its time

•• One of the 1One of the 1stst multimulti--player player gamegame


Tops 20Tops 20

•• The direct descendant of TOPSThe direct descendant of TOPS--10 10 •• Was available with a variety of higher level Was available with a variety of higher level

language compilers & application tools such as language compilers & application tools such as FORTRAN, COBOL, BASIC, ALGOL, CPL, FORTRAN, COBOL, BASIC, ALGOL, CPL, APL & DB Management APL & DB Management

•• Its architecture remained as it was designed in Its architecture remained as it was designed in 1969, development had started in 19731969, development had started in 1973

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Tops 20Tops 20

•• By By DECDEC, the second OS for the , the second OS for the PDPPDP--1010..•• Was very popular, when DEC tried to replaced Was very popular, when DEC tried to replaced

it with VMS in VAX (1980) most users left to it with VMS in VAX (1980) most users left to UnixUnix


VMSVMS--Virtual Virtual MemMem. System. System

•• Runs on the Runs on the VAXVAX and and AlphaAlpha familyfamily•• Designed for use in Designed for use in time sharingtime sharing, , batch batch

processingprocessing, , real timereal time•• Still used & developed today.Still used & developed today.


Operating SystemsOperating SystemsUnix Unix –– 1969+1969+

•• UnixUnix originally developed 1969 originally developed 1969 by a group of by a group of AT&TAT&T (MIT) (MIT) employees at employees at Bell LabsBell Labs on on PDPPDP--77

•• Originally named Originally named UnicsUnics


Operating SystemsOperating SystemsWindowsWindows

•• 11stst Windows Windows cooperative multitaskingcooperative multitasking include include Windows 1.0Windows 1.0 (1985) and (1985) and Windows 2.0Windows 2.0 (1987)(1987)

•• Windows/386Windows/386 introduced a 32introduced a 32--bit bit protected protected modemode kernelkernel and and virtual machinevirtual machine monitor monitor (1992)(1992)

•• Win 95/98/2000 and now XP (2001) & Vista Win 95/98/2000 and now XP (2001) & Vista (2006)(2006)


Operating SystemsOperating SystemsGooBuntoGooBunto

•• Google OS Google OS –– should be released at 2010should be released at 2010•• 6464--bit support, full multitasking & timebit support, full multitasking & time--sharingsharing


Operating SystemsOperating Systems-- More More --

•• Nowadays all OS are multitasking & TimeNowadays all OS are multitasking & Time--SharingSharing•• Most Most OSOS’’ss are implemented on 1950s conceptsare implemented on 1950s concepts

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TeleTypeTeleType

•• A A teleprinterteleprinter is a now called is a now called typewritertypewriter•• Used to communicate typed messages P2P often Used to communicate typed messages P2P often

by a pair of wiresby a pair of wires•• On 1922 the 1st teletypeOn 1922 the 1st teletype


ASRASR--3333 TeletypeTeletype

•• Teletype CorporationTeletype Corporation's ASR33 's ASR33 was a very popular model of was a very popular model of teleprinterteleprinter

•• Designed for lightDesigned for light--duty office use, duty office use, it was much flimsier and cheaper it was much flimsier and cheaper than its heavy duty cousin, the than its heavy duty cousin, the model 35ASRmodel 35ASR

•• These mechanical parts printed up These mechanical parts printed up to 10 characters per secondto 10 characters per second


TimeTime--Sharing MachinesSharing Machines

•• 1957 1957 -- IBM 704IBM 704 1961 1961 IBM 7090IBM 7090 –– both both were modified to the Timewere modified to the Time--Sharing Sharing conceptconcept

•• 1964 1964 -- IBM 360 and its successors are IBM 360 and its successors are the most profitable line of computer the most profitable line of computer systems in historysystems in history


TimeTime--Sharing MachinesSharing Machines

•• Common systems used for timeCommon systems used for time--sharing included sharing included the the SDS 940SDS 940(1966), the (1966), the PDPPDP--1010 (1968)(1968)

•• Later on Vax11/870 (1977) Later on Vax11/870 (1977) –– design for design for BSD UNIXBSD UNIXup to up to 4.3BSD4.3BSD, , UltrixUltrix--32 and 32 and VAXelnVAXeln OSOS


RefrencesRefrences

•• WikiPediaWikiPedia•• A History of MTS A History of MTS --

http://www.clock.org/~jss/work/mts/30years.htmlhttp://www.clock.org/~jss/work/mts/30years.html•• Batch VS TS Batch VS TS –– Bruce Bruce LakinLakin, NJ EDU Computer , NJ EDU Computer

Network 1980.Network 1980.•• A History of Modern Computing by Paul E A History of Modern Computing by Paul E

CeruzziCeruzzi..•• The McGrawThe McGraw--Hill Computer HandbookHill Computer Handbook•• IEEE Annals of the History of ComputingIEEE Annals of the History of Computing•• 234120 234120 -- Operating Systems Operating Systems –– CS TechnionCS Technion


ReferencesReferences

•• House of VAX: House of VAX: http://www.mcmanis.com/chuck/computers/vaxehttp://www.mcmanis.com/chuck/computers/vaxen/n/

•• VAX timeline: VAX timeline: http://research.microsoft.com/~gbell/digital/timelihttp://research.microsoft.com/~gbell/digital/timeline/32ne/32--bit.htmbit.htm

•• PDPPDP--1010: : httphttp://://wwwwww..columbiacolumbia..eduedu//acisacis//historyhistory//pdp10pdp10..htmlhtml

•• httphttp://://webcoursewebcourse..cscs..techniontechnion..acac..ilil//234118234118//•• wwwwww..computerhistorycomputerhistory..orgorg

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ReferencesReferences

•• http://historyhttp://history..sandiegosandiego..eduedu//GENGEN//recordingrecording//ccomputer1omputer1..htmlhtml

•• httphttp://://wwwwww..oldold--computerscomputers..comcom//historyhistory//detaildetail..asp?nasp?n==58&t58&t==44

•• http://http://www.poetproductions.comwww.poetproductions.com

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Time-Sharing - Israel Institute of Technologygotsman/236801/4-Time-Sharing.pdf · 2 Seminar in computer History CS236801 7 Why Time-Sharing is good Finance • Sharing devices –