Operating Systems Overview

Operating Systems Overview

• Operating system (OS) is a set of programs coordinating computer hardware resources.
• OS acts as an interface between the user and computer hardware.
• Popular OSs include Linux, Windows, OS X, VMS, OS/400, AIX, and z/OS.

Objectives Overview

• Explain basic operating system concepts.
• Describe the functions of an operating system.
• Understand the history of operating system development.
• Summarize features of several stand-alone operating systems.
• Briefly describe various server operating systems.
• Summarize features of several embedded operating systems.

What is an Operating System?

• OS performs tasks like file management, memory management, process management, input/output handling, and controlling peripheral devices (disk drives, printers).
• OS tasks include starting/shutting down a computer, providing a user interface, managing programs, establishing internet connections, managing memory, monitoring performance, and administering security.

Four Components of a Computer System

• Users interact with system and application programs.
• The operating system sits between application programs and computer hardware, providing an interface.
• Computer hardware runs everything.

Operating System Functions: Booting

• Booting: startup sequence starting the OS.
• Boot sequence: initial operations when switched on.
• Boot loader: program starting the "chain reaction" loading the entire OS.
• Boot device: device from which the OS is loaded (e.g., hard disk, optical drive, floppy drive, network interface card, USB device).

Operating System Functions: Shut Down Options

• Sleep mode: saves open documents to RAM, turns off unused functions, and puts the computer in a low-power state.
• Hibernate mode: saves open documents to a hard disk before removing power.

Operating System Functions: User Interface (UI)

• UI controls how users enter data/instructions and how information is displayed.
• Graphical User Interface (GUI): users interact with menus and visual images.
• Command-line Interface: users use the keyboard to input data/instructions.

Operating System Functions: Handling Programs

• OS handles programs directly affecting productivity.
• Single-user and multiuser: OS handles multiple user requests (e.g., multitasking).
• Single-tasking and multi-tasking features: run more than one program at once.
• Preemptive multitasking: OS takes control of programs executing, allowing others to run.

Operating System Functions: Processing Tasks

• OS determines order in which tasks are processed.
• Features like spooling (e.g. document printing) manage order of tasks.

Operating System Functions: Internet Connections

• Most OSs provide methods to connect to the Internet (e.g., dial-up, VPN).

Operating System Functions: Performance Monitor

• Performance monitor: program assessing and reporting information about computer resources and devices (e.g., CPU, disk, network).

Operating System Functions: Other Capabilities

• Manage files, search for files, view images, and secure the computer.
• Uninstall programs, clean up/defragment disks.
• Diagnose problems, backup files/disks.
• Set up screen savers.

Operating System Functions: Automatic Updates

• OS automatically provides updates to software programs.

Operating System Functions: Server OS

• Server OSs organize and coordinate resource access for multiple users.
• Network administrators use server OSs to add/remove users/devices, install software, and administer network security.

Operating System Functions: User Accounts

• Each user has a user account.
• User name (or ID): identifies a specific user.
• Password: private combination of characters associated with the user name.

Types of Operating Systems

• Stand-alone: complete OS for a personal computer, laptop, or mobile computing device.
  • Examples: Windows 7, Mac OS X, UNIX, Linux.
• Server: organize and coordinate resource access for multiple users.
  • Examples: Early Windows Server versions, Windows Server 2008, UNIX, Linux, Solaris, NetWare
• Embedded: OSs embedded within other devices and platforms.
  • Examples: Windows Embedded CE, Windows Mobile, Palm OS, iPhone OS, BlackBerry, Google Android, Embedded Linux, Symbian OS.

Stand-Alone Operating Systems: Windows 7

• Windows 7: Microsoft's fastest, most efficient OS to date.
• Available in multiple editions (Starter, Home Premium, Ultimate, Professional).
• Provides programs like Windows Firewall, Windows Media Player, Windows DVD Maker, and Desktop Gadgets.

Stand-Alone Operating Systems: Mac OS X

• Macintosh operating system sets the standard for ease of use.
• Latest version is Mac OS X.

Stand-Alone Operating Systems: UNIX and Linux

• UNIX: multitasking OS developed in the early 1970s.
• Linux: open-source, popular, multitasking OS, UNIX-type.

Utility Programs: File Manager

• File manager: utility program for file management functions.
• Tasks include displaying file lists, organizing files in folders, copying/renaming/deleting files, sorting files, and creating shortcuts.

Utility Programs: Search Utility

• Search utility: program for locating files based on specified criteria.

Utility Programs: Image Viewer

• Image viewer: displays, copies, and prints graphic file contents.

Utility Programs: Uninstaller

• Uninstaller: removes a program and related system files.

Utility Programs: Disk Cleanup

• Disk cleanup: utility searching for and removing unnecessary files (e.g., downloaded program files, temporary internet files, deleted files, unused program files).

Desktop vs. Server Operating Systems

• Server hardware can take various forms (traditional servers, rack-mounted servers, blade servers).
• Rack-mounted servers are CPU boxes that can hold multiple servers.
• All servers often share one monitor and pointing device.
• Blade servers look like cards fitting into an enclosure.

Servers

• A server controls access to hardware, software, and network resources.

Mainframes

• Mainframe: large, powerful computer handling hundreds/thousands of users simultaneously.

Supercomputers

• Supercomputer: fastest, most powerful computer, capable of processing more than one quadrillion instructions per second.

The Role of Application Software

• Application software: any program a user might run on a computer (e.g., word processor, spreadsheet, database, computer game).
• OS manages communication between applications, users, and the computer.
• Applications can run on any hardware as long as the OS controls them.

The Role of the BIOS

• BIOS: basic input/output system, low-level program code on the computer's motherboard.
• Resides on a chip, initiating/enabling communications with hardware devices.
• Performs power-on self-test (POST) startup tests.
• Initiates hardware and software communications; loads the main OS.

The Role of the BIOS: Flash Memory and CMOS

• BIOS is stored in a flash memory chip that doesn't lose data when the computer is off.
• Stored in CMOS memory (complementary metal-oxide semiconductor).
• When the computer turns on, the BIOS startup program executes. Test hardware components.
• Loads the operating system.

Multiuser Systems

• Multiuser systems support multiple users accessing the system simultaneously.
• Cloud computing is a multiuser system in which users can access resources from various shared resources on a network (e.g., laptop, smartphone, desktop computer, tablet).

Single Tasking vs. Multitasking

• Single-tasking OSes execute one program at a time.
• Multitasking OSes execute multiple programs concurrently.
• Cooperative multitasking: OS hands over control to a program then waits for the program to give control back.
• Preemptive multitasking: OS takes control of running programs.

Single-User vs. Multiuser Operating Systems

• Single-user OSs handle one user at a time.
• Multiple-user OSs support multiple users at a time.
• Often, server OSs are multiuser, while some desktop OSs have limited multiuser capabilities.