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Overview of PC Operating System. LI Xiang Telecommunication Division, NMC, China E-mail: lixiang@cma.gov.cn. An operating system is the software that provides the interface between the hardware of a computer system and the applications programs that are used on it. 1. Introduction to Windows.
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Overview of PC Operating System LI Xiang Telecommunication Division, NMC, China E-mail: lixiang@cma.gov.cn
An operating system is the software that provides the interface between the hardware of a computer system and the applications programs that are used on it.
1. Introduction to Windows • Windows is a series of operating systems developed by Microsoft. • Object oriented and easy-to-use Graphical User Interface (GUI) • Multitasking Operating systems • allowing multiple software processes to be run at the same time. • Multiprocessing • allowing multiple processors to be utilized. • Multithreading • allowing different parts of a software program to run concurrently. • Abundant in development tools and applications • Visual Basic, Visual C, Visual FoxPro, Delphi, Power Builder, ……. • Microsoft Office, Microsoft Visio, Internet Explorer,……
MS Windows kernal • Windows 9X kernal • Windows 3.X/95/98/ME • In 2001, Microsoft announced ceasing the development of Windows 9X kernal. • Windows NT kernal • Windows NT/2000/XP
Architecture of Windows 2000/XP Non OS service process, eg. WINLOGON, SMSS OS service process, eg. Event log service OS function call interface System support process Service process User application Environment subsystem Converting public calling interfaces to internal system calls Subsystem DLLs user mode kernel mode GUI • Memory management • Process and threads management • I/O • Process communication • Scheduling threads • Scheduling interrupt • Synchronizing multiprocessor Including the drivers of file system and hardware
Major components of Windows • Windows Desktop • Icons, Start Button, Taskbar • Control pannel • Configuration and management hardware • Configuration and management system resources • Install and uninstall application software • File manager • Files and folders • program files: executable • data files: not executable and associated with a specific program or file format • file naming • a file name can contain up to 255 characters including letters, numbers, spaces and some other printable characters. • a file name can’t contain the following characters: / \ : * ? " < > | • Tasks manager • Displaying the status of processes current running on system • Stopping a process • Network • Supporting NetBEUI, TCP/IP, IPX, …… • Providing the network application programs and tools, such as ftp, telnet, ping, tracert, netstat,…… • Allowing sharing disks, files and printers among MS Windows machines.
2. Introduction to Unix • Developed at Bell Laboratories in 1969. • Written with the high-level programming language C. • Initially designed for medium-sized minicomputers, and then moved to mainframe computers and personal computers. • For different hardware platforms, there are many different Unix versions. • AIX, Digital Unix, Hp Unix, …… • Sco Unix, which is a PC-based Unix operating system
Features of Unix • Mature and stable operating system • Graphical User Interface operating system • Multitasking capability • Multiprocessing • Multithreading • Multiuser capability • allowing multiple users to utilize the computer and run programs at the same time. • System portability • Capable of moving from one brand of computer to another with a minimum of code changes . • The operating system could be upgraded without having all the user's data inputted again. • Containing many tools and applications
Unix functionally organized at three levels • - Surrounding the kernel and acting as a user interface to the Unix operating system • - Command language interpreter • - Interprets the command users enter • - Selects and runs the command or program • - Provides the results to the screen or file as • directed by the command • C shell, Bourne shell, Korn shell offering additional functionality to the operating system Tools and applications shell • The main part of operating system, and responsible for controlling system resources. • Loaded into memory when the system boots • Process control and scheduling • Memory management • Device I/O • System error handling • User programs requesting services from the kernel through system calls • Hardware devices getting kernel response through interrupts kernel
User interface • Providing two methods for user to interact with the operating system • GUI, for users of workstations or intelligent terminals with bit-mapped displays. • Command line interface, for users of a character cell terminal or terminal emulator.
File system • A hierarchical file system • a root filesystem: /bin, /lib, /etc, /dev,…… • a /usr filesystem: programs and unchanging data • a /var filesystem: changing data (such as log files) • a /home filesystem: user’s files • Types of files • Ordinary disk files • Special files • Each physical device on a Unix system is treated as a special file. • Located in the /dev directory. • Directory flies • Naming files and directories • File and directory names can include letters, numbers, periods(.), underscores(_), and some other printable characters. • Avoid characters with special programming or system meanings, such as /, *?[]<>$’”&!. • Generally, a name of file and directory can contain up to 255 characters. • Accessing directories and files • Accessing directories: cd , ls, pwd • Finding files: find • Viewing files: more, cat, tail, head • Editing files: vi, ed
Controlling Processes (1) • A process • Is a program that is currently executing • Can be created and destroyed • Has resources allocated to it • Has an environment associated with it that: • Process and process group IDs • Open files • Working directory • File creation mask • Real and effective user and group IDs • Resource limits: maximum file size, maximum amount of memory • Signal action settings • A set of named variables • Can create other processes • Can communicate with other processes
Controlling Processes (2) • Creating a process • Running jobs in the foreground: command • Running jobs in the background: command & • Obtaining process status • jobs • Displays status of jobs in the current session • Job number, job status, PID • ps • Shows current status of processes • PID, state, accumulated execution time, command, …… • Controlling and managing jobs • Placing a job in the foreground: fg • Restarting a job in the background: bg • Stopping a process: Ctrl/C, kill • Setting process priority: nice • Scheduling jobs to run at appropriate times: at, crontab
Networking Services • UUCP • Unix to Unix copy program • A batch-processing/spooling system • Typically used between systems with dial-up telephone lines or direct serial lines • TCP/IP • rlogin, rcp, rsh, telnet, ftp • Ping, netstat, trouceroute • Network File System (NFS) • Allowing transparent file access over TCP/IP networks among computers, including Unix, Linux and MS Windows machines. • IPX/SPX • Netware clients can log in Unix servers via Novell network. • LAN Manager Client • allowing the sharing of files with MS Windows machines (via Network Neighbourhood). • allowing the sharing of printers across machines.
Online documentation • Unix commands are documented on line in the man pages. • The man command provides online access to the system's reference pages.
3. Introduction to Linux • Afree Unix-type operating system originally created by Linus Torvalds with the assistance of developers around the world. • The source code for Linux is freely available to everyone. • GUI operating system, including many of the tools that Windows users are familiar with such as, • A file manager • A Window manager • A help system • A configuration • ……. • Requiring less system resources. A Linux based system can operate smoothly on a 386 or 486. • Application software support • Office applications: Corel WordPerfect Office 2000 for Linux Deluxe • Graphics tool: Gimp • Browsers: Netscape Communicator 4.75, Opera browser
Examples • PCVSAT, DVB, DAB • MS Windows • CMA’s domestic communication system • NICC: AIX • RICC, PICC: AIX, Digital Unix • CIMS: Sco Unix, will be replaced by Linux in future. • CMA’s GTS system • VMS, will be replaced by UNIX in next year
TCP scokets FTP (put) FTP (get) PCVSAT receiver - PC - Windows 98 Data management - PC - Sco Unix Database - PC - Sco Unix - Sybase • Data management and storage • IBM H50 • - AIX • - Sybase PCVSAT Mux - PC - Windows NT CIMS NICC