DAI-C1-UD 2 Introduction To Operating Systems Academic Year DAI. Credit 1 (Single and Multiuser Operating Systems) Ferran Chic PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO) DAI-C1-UD 2

SYSTEM Set of elements that make possible the automatic management of information in organizations such as Enterprise University School At Home Shop PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

COMPONENTS OF A SYSTEM HARDWARE OPERATING SYSTEM APPLICATION PROGRAMS USERS SOFT WARE PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

APPLICATION SOFTWARE Suites Suites (Worksheets, DataBases, Text Editors, Slide Makers...) (Worksheets, DataBases, Text Editors, Slide Makers...)  OpenOffice  Office WEB BROWSERS WEB BROWSERS  Mozilla  Opera  IE SPECIFIC APPS. SPECIFIC APPS.  CAD  DIDACTICAL : Encarta, Clic,…  MATHEMATICAL: SPSS, MATLAB... Enterprise Software Enterprise Software  Selling and Buying process: Invoices, storage, orders  accounting,  Production control... PROGRAMS FOR MAKING OTHER PROGRAMS PROGRAMS FOR MAKING OTHER PROGRAMS  Compilers  Interpreters  Assemblers  DBMS & CASE TOOLS PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

OPERATING SYSTEM Interface between User and Hardware Hardware resource manager Virtual Machine ( it provides easy interfaces to access hardware ). It’s such an abstraction layer that allows users to forget about hardware details. O.S. Provides necessary resources to users in order to succeed in executing programs PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

O.S. Provides support tools to users Command interpreters (shell) File and web browsers Drivers Editors Compilers Device configuration assistants Graphic administration and monitoring tools PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

O.S. Definition Set of programs that aim to Act as an interface between user and computer to allow users to interact with the machine in a simply way (virtual machine) Optimize hardware resources and software stored in the machine PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

VON NEUMANN MACHINE Components of this machine: CPU INTERNAL MEMORY I/O DEVICES STORAGE SYSTEM BUS SUBSYSTEM PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

I/O SUBSYSTEMS Nowadays, computers have several I/O subsystems, grouped1 by functionality. Every subsystem could be even an independent processor. I/O subsystem for HARD DISKS I/O subsystem for CD/DVD I/O subsystem for keyboard & mouse PCI I/O subsystem for expansion cards (NIC, sound, …) DISPLAY I/O Subsystem PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

Programs and data are permanently stored in … Where do we store programs? Where do programs are executed? STORAGE DEVICES (“Memoria secundària”) A program has instructions in machine code. When an instruction needs to be executed it is transferred with the necessary data to MAIN MEMORY CPU (processor) When a program needs to be executed, instructions & data needed must be transferred to Results of instruction execution are stored into Eventually, if you need to store results permanently, they need to be transferred to PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

O.S. From user point of view Hardware Operating System System Software Application Software Users PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

O.S. IS ALSO A RESOURCE MANAGER CPU Time sharing MAIN MEMORY Program location Data location Sharing Data and Programs I/O DEVICES Performance on I/O Transfers Virtual machine for users PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

O.S. ACTS AS AN INTERFACE BETWEEN USER AND HARDWARE Programs establish hardware communication via system calls provided by the operating system itself. We have system calls for everything you need Keyboard access File management Make memory reservation for programs and data Dispose memory Access to all devices Network access etc PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

O.S. CLASSIFICATION SINGLE USER / MULTI USER SINGLE TASK / MULTI TASK TIME SHARED / REAL TIME MULTI THREADING PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

SINGLE USER vs MULTI USER Single User O.S. O.S. can deal with only 1 user at the same time MS DOS Multi User O.S. O.S. has access control for many users. As far as resources are concerned, every user has ACL’s to establish the privileges between users and resources W2K Professional, WXP Linux Windows 2000 Server, Windows 2003 server PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

TIME SHARING OPERATING SYSTEM Process : program being executed (in execution progress) In a time sharing O.S. we have many programs virtually executing at the same time The truth is that in a “time slice” only one instruction of only one program is being executed into CPU. In fact, one instruction could take several clock periods. Time sharing O.S. give N “time slices” to every process. During this time, this process is being executed inside CPU. Once a process has run out of time, the process leaves from CPU and another process takes CPU control. CPU SCHEDULER is an O.S. program that is in charge of doing the time slice assignments to all the processes that need instruction execution.. PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

REAL TIME O.S. Some critical processes need to be executed without interruptions and they need to be executed as soon as possible. A time sharing policy is not allowed. A real time O.S. is a specialist in executing critical processes without interruption. PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

MULTI THREADING O.S. Suitable for SMP (symetric multiprocessor) Process divided into serveral execution threads With more than one CPU, different threads are assigned to different CPU’s PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

KERNEL : Functions Main O.S. program It provides services to any program that requires some resources Communication with the kernel is done via system calls Responsible for CPU scheduling Responsible for MAIN MEMORY scheduling Responsible for I/O scheduling Responsible for Networking as well Built in device drivers All that we can request to the system must be supported by the kernel PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

DOS O.S. STRUCTURE msdos.sys command.com io.sys PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)

UNIX O.S. STRUCTURE PELE-08/11 (Pla Experimental Llengües Estrangeres).Potenciació de la llengua Anglesa a la FP) © Ferran Chic. DAI-1er- C1 (SO)