Operating Systems. Topics OS Definition Types of PC OS Functions of OS Terms and Concepts DOS Commands.

Operating Systems

Lesson 4 0x004

100

Topics

OS Definition Types of PC OS Functions of OS Terms and Concepts DOS Commands

Operating 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.

Examples of PC OS

Windows 98

MicrosoftWindows Me, NT, 2000, XP, Vista, 7, 8 (Client)Windows 2000, 2003 , 2008, 2012 (Server )

MacintoshMac OS X snow LeopardMac OS X LionMac OS X Mountain Lion

Examples of PC OS (Cont.)

LinuxChrome OSOS/2

Examples of Mobile Devices OS

-iOS 5-iOS 6-iOS 7

-Windows 7 m-Windows 8 m

Microsoft

-Android 4 Ice Cream Sandwich -Android 4.2Jelly Beans -Android 4.3 Kit Kat

Mobiles OS

Functions of the operating systems

1. Input and output: allows computer to display and get data from the I/O devices to interact with users.

2. Memory and secondary storage management:

1. allows the user to organize their data on secondary storage into files & folders

2. also manages the use of main memory by splitting main memory into two parts (user area, system area).

3. 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.

4. Communication: it is the ability to a computer to communicate with other computers to transfer programs and data.

5. 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).

6. Program Execution Environment : OS loads the program into the memory and manage program execution

7. Security: make sure that only authorized users can access computer.

Functions of the operating systems (cont.)

Operating System

Input/Output

Accounting

Memory and storage Management

Communication

Security Time Sharing

Program Execution Environment

Functions of the operating systems as a diagram

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Components of an operating system

1. The Executive or Supervisor2. The Command Interpreter 3. The Internal Commands4. The External Commands

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Components 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).

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1. 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.

Components of an operating system (cont.)

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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

Components of an operating system (cont.)

OS Terms and Concepts

Graphical User Interface GUI: 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.

OS 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.

OS Terms and Concepts

Virtual Memory ( swapping or paging file): A+ book p53

How It 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).

Why Modern 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.

Disadvantages The disadvantage here is that it is not as fast as the real

memory.

Setting up Win XP virtual memory

Examples of DOS Commands A+ book p 384-386

Ver: used to display the windows version. CD: Change the current directory

Format: used to format a disk. MD: create directory

Cls: used to clean the screen. Rd: delete file or directory

Chkdsk: checks a disk and display status report.

Edit: create file

Fdisk: it enables you to create Hard disk partions

Copy: copy one or more files from one place to another

Date: display or change the date Del: delete one or more files

Time: Used to display or change the timeLabel : Creates, changes, or deletes the volume label of a disk.