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Overview of PC Operating System

LI Xiang

Telecommunication Division, NMC, China

E-mail: lixiang@cma.gov.cn

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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.

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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,

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Convertingpublic callinginterfaces tointernalsystem calls

Architecture of Windows 2000/XP

Subsystem DLLs

GUIExecutive

kernel Device Drivers

Hardware Abstraction Layer

kernel mode

user mode

OS function callinterface

OS service process, eg.Event log service

Systemsupportprocess

Serviceprocess

Userapplication

Environmentsubsystem

Non OS service process,eg. WINLOGON, SMSS

Scheduling threads Scheduling interrupt

Synchronizing multiprocessor

Including the drivers of file

system and hardware

-Memory management

-Process and threadsmanagement

- I/O

-Process communication

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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, spacesand some other printable characters.

a file name cant 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.

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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

2. Introduction to Unix

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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 runprograms 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

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- Surrounding the kernel and acting as a userinterface 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 asdirected by the command

-C shell, Bourne shell, Korn shell

Unix functionally organized at three levels

shell

Tools and applications

The main part of operating system, andresponsible for controlling system resources.-Loaded into memory when the systemboots

-Process control and scheduling-Memory management-Device I/O-System error handling-User programs requesting services fromthe kernel through system calls

-Hardware devices getting kernel responsethrough interrupts

kernel

offering additionalfunctionality to theoperating system

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User interface

Providing two methods for user tointeract with the operating system

GUI, for users of workstations orintelligent terminals with bit-mappeddisplays.

Command line interface, for users of acharacter cell terminal or terminalemulator.

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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: users 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

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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

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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

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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.

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Online documentation

Unix commands are documented online in the man pages.

The man command provides onlineaccess to the system's reference pages.

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3. Introduction to Linux

Afree Unix-type operating system originally created by LinusTorvalds 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 canoperate 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

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Examples

PCVSAT, DVB, DAB

MS Windows

CMAs domestic communication system NICC: AIX

RICC, PICC: AIX, Digital Unix

CIMS: Sco Unix, will be replaced by Linux in future.

CMAs GTS system

VMS, will be replaced by UNIX in next year

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Data managementand storage

- IBM H50

- AIX

- Sybase

PCVSAT Mux

- PC

- Windows NT

FTP

(get)

FTP

(put)

TCPscokets

NICC CIMS

PCVSAT receiver

- PC

- Windows 98

Datamanagement

- PC

- Sco Unix

Database

- PC

- Sco Unix

- Sybase

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Thank you