2Topics OS Definition Types of PC OS Functions of OS Terms and Concepts DOS Commands
3Operating Systems Operating System Is a set of programs which manage all operations of the computer system, and enables the user to interact with the hardware ‘HW’.It provides a consistent environment for other software to execute commands.
4Examples of PC OS Microsoft Windows Me, NT, 2000, XP, Vista, 7, 8 (Client)Windows 2000, 2003 , 2008, 2012 (Server )Windows 98MacintoshMac OS X snow LeopardMac OS X LionMac OS X Mountain Lion
6Examples of Mobile Devices OS Mobiles OS-iOS 5-iOS 6-iOS 7-Android 4 Ice Cream Sandwich-Android 4.2Jelly Beans-Android 4.3 Kit KatMicrosoft-Windows 7 m-Windows 8 m
7Functions of the operating systems Input and output: allows computer to display and get data from the I/O devices to interact with users.Memory and secondary storage management:allows the user to organize their data on secondary storage into files & foldersalso manages the use of main memory by splitting main memory into two parts (user area, system area).Time sharing: operating system can allow more than one user to work on the same computer, and run more than one program at the same time.
8Functions of the operating systems (cont.) Communication: it is the ability to a computer to communicate with other computers to transfer programs and data.Accounting: this is to keep track of what each user has done on the computer, to bill each for the resources used(if necessary). (for each user a separate account).Program Execution Environment : OS loads the program into the memory and manage program executionSecurity: make sure that only authorized users can access computer.
9Functions of the operating systems as a diagram Input/OutputMemory and storage ManagementOperating SystemSecurityTime SharingProgram Execution EnvironmentCommunicationAccounting
10Components of an operating system The Executive or SupervisorThe Command InterpreterThe Internal CommandsThe External Commands
11Components of an operating system (1) The executive or supervisor:this is the main part of the operating system.it is a memory resident program which stays in RAM as long as the computer is on.it supervises all operations like data storage and memory access.The supervisor is loaded into main memory at switch-on time by a small program in ROM called the Bootstrap loader. this program looks for the supervisor program on the first track on the disk(boot sector). It loads the supervisor into the ram and runs it, this process is called(Booting the system).
12Components of an operating system (cont.) (2) The command interpreter:each operating system has a set of commands, each command has a valid syntax.the command interpreter interprets each command issued by the user and calls for the appropriate program from the operating system to carry out the command.If there is a syntax error, it will notify the user and may lead the user how to handle it.
13Components of an operating system (cont.) (3) The internal commands:those are the mostly used commands set, they remain in the ram.Examples: Dir, Cd, Ren, …etc.(4) The external commands:Large and less frequently used commands.They kept in the disk to save the ram space, they will be loaded in ram once they are used.Examples: Format, Diskcopy, Fdisk ..etc
14OS Terms and Concepts Graphical User Interface GUI: Shell: The method by which a person communicates with a computer. It uses a mouse, touch pad, icons to interact with the computer.Shell:A program that runs on top of the OS and allows the user to issue commands through a set of menus or GUI.Networking Operating System NOS:Similar to a standard OS, except that the NOS is optimized to provide services to other machines on the network.
15OS Terms and Concepts Cooperative Multitasking: A multitasking method that depends on the application itself to be responsible for using and then freeing access to the processor.Preemptive Multitasking:A multitasking method in which the OS allots each application a certain amount of processor time and then forcibly takes back control and gives another application or task access to the processor.Multithreading:The ability of a single application to have multiple requests in to the processor at one time.
16OS Terms and ConceptsVirtual Memory ( swapping or paging file): A+ book p53HowIt uses what is called a swap file, or paging file.A swap file is actually hard drive space into which idle pieces of programs are placed, while other active parts of programs are kept/swapped into main memory ( RAM).WhyModern applications requires huge memory to run.Also a lot of programs can work at the same time, so virtual memory takes the advantage of the vast nature of recent computer programs.DisadvantagesThe disadvantage here is that it is not as fast as the real memory.
17Examples of DOS Commands A+ book p 384-386 Ver: used to display the windows version.CD: Change the current directoryFormat: used to format a disk.MD: create directoryCls: used to clean the screen.Rd: delete file or directoryChkdsk: checks a disk and display status report.Edit: create fileFdisk: it enables you to create Hard disk partionsCopy: copy one or more files from one place to anotherDate: display or change the dateDel: delete one or more filesTime: Used to display or change the timeLabel : Creates, changes, or deletes the volume label of a disk.