Introduction to Operating Systems Chapter 1 Introduction to Operating Systems

Hardware Needs Software to Work Physical components of the computer (monitor, keyboard, memory chips, hard drive, etc.) Software Set of instructions that directs hardware to accomplish a task

Hardware Needs Software to Work

Software Programs written by programmers that instruct computers to perform specific task. PC Software Firmware (BIOS) Operating Systems (OS) Applications software BIOS and OS Control the computer when it is first turned on

Software BIOS and OS Control the computer when it is first turned on Startup BIOS Operating System Hardware 1.-Performs startup tasks 2.-Passes control to OS 3.-Performs more startup tasks

O. S During Operation O.S. is serving as a middle layer between User Application Software Operating System BIOS Device Drivers H a r d w a r e During Operation O.S. is serving as a middle layer between app software and hardware O.S. controls the allocation and use hardware

O. S. Components This component tracks every file in the system The kernel's primary purpose is to manage the computer's resources and allow other programs to run and use these resources.

O. S Operating System’s Tasks Memory Management Device Management Allocates portions of memory to programs at their request Device Management Recognizing input from the keyboard or mouse Sending output to the video screen or printer Storage Management Keeping track of files on the storage devices and hard drives Application Interface Ensures that applications continue to run when hardware upgrades and updates occur. User Interface GUI Command line

O. S (Tasks) Applications Operating System Kernel

Single and Multi-User O. S. Single User/Single Tasking Allows only one user to run one program at a time. Multi-User: Allows 2 or more users to run programs at the same time (some OS permit hundreds or even thousands of concurrent users) Multitasking Allows more than one program to run concurrently Multiprocessing Supports running a program on more than one CPU Multithreading Allows different parts of a single program to run concurrently Real Time Responds to input instantly. General-purpose OS, such as DOS and UNIX, are not real-time.

Single and Multi-User O. S. System Single user Multi-user Single task DOS X   Windows3.1 Windows95/98/Me WindowsNT/2000 WindowsXP Unix / Linux MAC/OS X VMS

Network O. S. (NOS) Network operating systems (NOS) coordinate the activities of multiple computers across a network. The network operating system acts as a director to keep the network running smoothly. The two major types of network operating systems are: Peer-to-Peer or Workgroup model Client/Server

Network O. S. (NOS) Peer-to-Peer Examples: AppleShare and Users share resources and files located on their computers and to on other computers Do not have a file server or centralized management All computers have the same ability to use the resources available on the network It is designed primarily for small to medium local area networks Peer-to-Peer Examples: AppleShare and Windows for Workgroups The file servers provide access to resources and security. It provides the mechanism to integrate all the components of the network Allows the network to centralize functions and applications in one or more dedicated file servers When server goes down, operations will cease across the network. Multiple users can simultaneously share the same resources irrespective of physical location. All components (client/network/server) work together Individual workstations (clients) have access to the resources available on the file servers. Client/Server Examples: Novell Netware and Windows NT Server .