Tài liệu Operating System Basics doc

• Resource Manager- Resource include: CPU, memory, disk, network - OS allocates and de-allocates these resources • Virtual Machine - provides an abstraction of a larger or just different

lesson 11

Operating System

Basics

• Resource Manager

- Resource include: CPU, memory, disk, network

- OS allocates and de-allocates these resources

• Virtual Machine

- provides an abstraction of a larger (or just different machine)

- Example:

- Virtual memory: looks like more memory

- Java: pseudo machine that looks like a stack machine

- IBM VM: a complete virtual machine

• Multiplexor

- allows sharing of resources and protection

What is an Operating System

• Provider of Services

- includes most of the things in the above definitions

- provide “common” subroutes for the programmer

- windowing systems

- memory management

• The software that is always loaded/running

- generally refers to the OS kernel

- small protected piece of software

• All of these definitions are correct

- but not all operating have all of these features

What is OS (cont.)

• Robustness

- detect and gracefully handle all invalid input

- should not be possible to crash the OS

• Consistency

- same operation should mean the same thing

* read from a file or a network should look the same

* a “-” flag should be the same in different commands

- conventions

* define the convention

Usability Goals

• Proportionality

- simple, common cases are easy and fast

* good default values

- complex, rare cases are possible but more complex and slower

* “rm” should give a warning

* formatting the disk should not be on the desktop next to the trash can

Usability Goals (cont.)

This lesson includes the following sections:

• The User Interface

• Running Programs

• Managing Files

• Managing Hardware

• Utility Software

• Graphical User Interfaces (GUIs)

• Graphical User Interfaces (GUIs)

• Most modern operating systems, like Windows and

the Macintosh OS, provide a graphical user interface (GUI).

• A GUI lets you control the system by using a mouse

to click graphical objects on screen.

• A GUI is based on the desktop metaphor Graphical

objects appear on a background (the desktop),

representing resources you can use.

The User Interface

- Graphical User Interfaces (GUIs)

Start menu Start button Taskbar

Desktop

Dialog box

Program running in

a window Window control buttons

• Icons are pictures that represent computer

resources, such as printers, documents, and

The User Interface - GUI Tools

Or, icons can be double-clicked to launch programs.

The Windows start button can be used

to launch programs.

• Applications designed to run under one operating

system use similar interface elements.

• Under an OS such as Windows, you see a familiar

interface no matter what programs you use.

• In a GUI, each program opens and runs in a separate window—a frame that presents the program and its documents.

• In a GUI, you can run multiple programs at once,

each in a separate window The application in use is said to be the active window.

The User Interface –

Applications and the Interface

Titlebar Menubar Toolbar

Scroll arrow

Scroll box Scroll bar Click the Minimize button to reduce

the program to a button on the taskbar Click the Maximize button to restore the window to its previous size. Click the Close button to close the window altogether.

• GUI-based programs let you issue commands by

choosing them from menus.

• A menu groups related commands For example, the

File menu's commands let you open, save, and print document files.

• Menus let you avoid memorizing and typing

command names.

• In programs designed for the same GUI, menus and

commands are similar from one program to another.The User Interface - Menus

• A dialog box is a special window that appears when

a program or the OS needs more information

before completing a task.

• Dialog boxes are so named because they conduct a

"dialog" with the user, asking the user to provide more information or make choices

The User Interface - Dialog Boxes

• Some older operating systems, such as DOS (Disk Operating System) and UNIX, use command-line interfaces.

• In a command-line interface, you type commands at a prompt.

• Under command-line interfaces, individual applications do not need to look or function the same way, so different programs can look very different

.

The User Interface - Command-Line Interfaces

The DOS Prompt is not seen much these days!

• Basic Services

• Sharing Information

• Multitasking

Running Programs

• The operating system manages all the other

programs that run on the PC.

• The operating system provides services to programs

and the user, including file management, memory management, and printing

• To provide services to programs, the OS makes

system calls—requesting other hardware and

software resources to perform tasks.

Running Programs - Basic Services

• Some operating systems, such as Windows, enable

programs to share information.

• You can create data in one program and use it again

in other programs without re-creating it.

• Windows provides the Clipboard, a special area that stores data cut or copied from one document, so

you can re-use it elsewhere.

Running Programs - Sharing Information

2

Information is clipped

from one application (Excel)

Using the clipboard Viewer to

examine the information

• Multitasking is the capability of running multiple

processes simultaneously.

• A multitasking OS lets you run multiple programs at

the same time.

• Through multitasking, you can do several chores at

one time, such as printing a document while

downloading a file from the Internet.

• There are two types of multitasking: cooperative and

preemptive

Running Programs - Multitasking

• The operating system keeps track of all the files on each disk.

• Users can make file management easier by creating

a hierarchical file system that includes folders and subfolders arranged in a logical order

Managing Files

• The OS uses interrupt requests (IRQs) to maintain

organized communication with the CPU and other pieces of hardware.

• Each hardware device is controlled by a piece of

software, called a driver, which allows the OS to activate and use the device.

• The operating system provides the software

necessary to link computers and form a network Managing Hardware

A utility is a program that performs a task that is not typically handled by the operating system.

Some utilities enhance the operating system's

• Explain how the OS enables users to manage files.

• List three hardware management tasks performed by

an OS.

• Name five types of utility software.

Project 4 due Oct 29

• Login to Unix or Linux machine and run the following commands: