Lesson 1 Lecture.pdf

Guide to Operating Systems, 6 th...

Guide to Operating Systems, 6 th Edition Module 1: Operating Systems Fundamentals ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 1  Learning Objectives By the end of this module, you should be able to: Explain basic operating system concepts Describe the categories of operating systems Discuss the primary roles of an operating system Describe the five major operating system components List several current general-purpose operating systems ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 2 An Introduction to Operating Systems (1 of 2) A computer’s functions and features can be broken down into three basic tasks all computers perform: − Input − Processing − Output The functions above involve some type of computer hardware − However the hardware is controlled and coordinated by the operating system (OS) ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 3 An Introduction to Operating Systems (2 of 2) An OS is a specialized computer program that provides the following features: − User interface − Storage management − Process and service management − Memory and I/O management − Security and resource protection − Kernel ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 4  Operating System Categories There are three broad categories of operating systems: − Single-tasking versus multitasking − Single-user versus multiuser − General-purpose versus real-time ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 5 Single-Tasking Versus Multitasking Operating Systems A single-tasking operating system can execute only a single process at a time − An embedded system is a computing device designed for a specific task and uses a single-tasking OS A multitasking operating system quickly switches between all the processes that are loaded into memory and scheduled to run − There are two general types of multitasking:  Cooperative multitasking – the OS gives CPU control to a process and waits for it to terminate or enter a waiting state  Preemptive multitasking – the OS is in control of the computer at all times ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 6  Single-User Versus Multiuser Operating Systems A single-user operating system allows only one user at a time to interact with the OS user interface, start processes, make system configuration changes, and interact directly with the file system − Windows 10 and earlier Windows client versions are arguably single-user systems A multiuser operating system allows multiple users to sign in to it, start and stop processes, interact with the user interface, and access the local file system − Linux/UNIX OSs have always supported multiple users, and Windows Server versions also allow multiple users through Remote Desktop Protocol (RDP) ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 7 General-Purpose Versus Real-Time Operating Systems A general-purpose operating system is designed to provide a convenient user interface and run applications in a home or business environment with reasonable performance. − Examples: Windows, Linux, Unix, macOS, and Android A real-time operating system (RTOS) is designed to process inputs and produce outputs in a very specific and repeatable amount of time − Examples: OSs for embedded systems such as VxWorks and QNX ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 8  Operating System Roles OSs can be defined by the role they play from the perspective of the user Most OSs can be classified as one of the following: − Client − Server − Standalone ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 9  Client Operating Systems The primary purpose of a client operating system is to run applications requested by a user and request data from network servers as necessary − Client OSs are usually installed on desktop or laptop computers and mobile devices and use a graphical user interface (GUI) − Client OSs usually include client versions of many network applications  For example, Windows 10 comes with Client for Microsoft Networks for accessing shared files and printers − Most client OSs are performance-tuned for running foreground applications (user applications) instead of background services ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 10  Server Operating Systems (1 of 3) The primary purpose of a server operating system is to share network resources and provide network services to clients Examples of server OSs include Windows Server, macOS Server, UNIX, and many Linux distributions Server OSs usually come with a DHCP server, a DNS server, a file server protocol, a Web server, and perhaps a directory service such as Microsoft’s Active Directory ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 11  Server Operating Systems (2 of 3) Server OSs often have built-in functions for the following: − Fault tolerance is the ability of a system to recover from a hardware or software failure − A server OS typically supports clustering, which is the ability of two or more servers to act as one − A load-sharing cluster has two or more servers that alternate in taking client requests − Many servers also support hot swapping of components such as hard disks, memory, or even processors so that if a computer fails, a new component can be swapped − For scalability, some servers support hot adding of components so that more storage, RAM, or processors can be added while the system is running ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 12  Server Operating Systems (3 of 3) A server OS is usually installed on a more powerful computer that may have several high-speed network interfaces and terabytes of storage The hardware of a server must support fault-tolerant features such as hot swapping and failover clustering − Server hardware can take different forms, including traditional tower computers, rack-mounted servers, and blade servers ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 13  Standalone Operating Systems A standalone operating system is not designed to interact with other OSs or access network resources Most standalone OSs run on embedded systems OSs that run older or isolated traffic signal systems are likely to be standalone − As are the OSs that run automobile electronic systems and industrial machinery This is changing as computer-controlled devices are being built with IoT in mind − So operational and performance data from these devices can be collected and analyzed to make processes more efficient ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 14  Primary Operating System Components Here are the five main OS components: − The boot procedure − Process and service management − Memory and I/O management − Security and resource protection − The kernel ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 15  The Boot Procedure (1 of 4) The boot procedure is a series of steps performed by every computing device that starts with power to the CPU and other hardware components and ends with a running system ready to perform work The boot procedure can be broken down into six general steps: − 1. Power is applied to the CPU and other hardware components − 2. The CPU starts − 3. The CPU executes the firmware startup routines − 4. The operating system is located by the firmware − 5. The OS is loaded into RAM − 6. OS processes and services are started ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 16  The Boot Procedure (2 of 4) Firmware is program code that is stored on computer hardware in non-volatile memory and is responsible for performing diagnostic tests and booting the OS Non-volatile memory is memory that maintains its contents when no power is applied to the system − It is typically flash memory in modern systems or electrically erasable programmable read- only memory (EEPROM) in older systems Firmware is called the BIOS or UEFI in newer systems Firmware contains an initial bootstrap program that locates and then loads the bootloader program, which is responsible for loading the initial process that makes up the OS ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 17  The Boot Procedure (3 of 4) The basic input/output system (BIOS) and Unified Extensible Firmware Interface (UEFI) are firmware programs that play a part in the boot process The BIOS has the following properties and performs the following tasks: − Resides on a chip on the computer’s motherboard − Initializes I/O devices − Performs tests at startup, such as memory and hardware component tests called the power- on self-test (POST) − Provides a user interface to allow hardware configuration such as CPU overclocking or disk configuration − Locates and loads the OS that interfaces with the user ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 18  The Boot Procedure (4 of 4) BIOS configuration is stored in a complementary metal oxide semiconductor (CMOS) memory chip Users can make changes to the BIOS configuration by accessing the BIOS setup screen before the computer boots When a PC is turned on: − The machine wakes up and begins executing a startup program inside the BIOS − This program initializes the screen and keyboard, tests hardware, and initializes the hard disk and other drives − The main operating system is loaded onto the hard disk ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 19  Process and Service Management A process is a program that is loaded into memory and executed by the CPU A program can be a user application, an OS service, or even the kernel On a Windows 10 system, you can see all running processes by using Task Manager Background processes listed by Task Manager are not essential for the OS to function Windows processes are required for full system functionality and include the registry service, user interface components, network services, interrupt handlers, and logon services ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20  Memory and I/O Management (1 of 2) Memory is managed by a dedicated memory manager that runs in kernel mode When a process is loaded and started, the OS must allocate enough memory for the process and its data − When a process terminates, the OS must mark the memory as free so other processes can use it I/O management is required to prevent more than one process from accessing an I/O device at the same time ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 21  Memory and I/O Management (2 of 2) Interrupts − Polling is a process where the OS checks each device one after the other in a round-robin fashion to see if it requires attention − Because of the shortcomings of polling, most systems use interrupts − An interrupt is a signal, usually generated by an I/O device, that alerts the CPU and OS that a device needs attention − Pins on a CPU are usually called interrupt request (IRQ) lines  When the CPU detects the IRQ line, it stops what it is doing, determines the source of the interrupt, and starts execution of the interrupt service routine (ISR), also referred to as an interrupt handler ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 22  Security and Resource Protection Modern general-purpose OSs and RTOSs running on embedded systems provide controls to prevent unauthorized access to the system and its data Authentication and Authorization − Authentication verifies that an account trying to access a system is valid and has provided valid credentials (username and password) − Authorization verifies that an authenticated account has permission to perform an action on a system ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 23  The Kernel The kernel runs with the highest priority on the system Scheduling computer processes and managing resources are key tasks of the OS kernel Jobs performed by the kernel can include the following: − Managing interactions with the CPU − Managing interrupt handlers and device drivers − Handling basic computer security − Managing use of the computer’s memory − Managing priority levels assigned to programs and computer processes ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 24  Summary (1 of 2) All computers perform three basic tasks: input, processing, and output An operating system (OS) provides the foundation upon which to run the components of a computer and execute applications A basic task of an OS is to enable a computer to perform I/O functions so that it can use software applications and communicate with computer hardware OSs can be understood in terms of characteristics such as time sharing, real- time operation, and multiuser capabilities Early OSs tended to be single-tasking, but modern systems are largely multitasking ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 25  Summary (2 of 2) A true multiuser system is one in which multiple users access and run a single application on a single computer at the same time Two common types of OSs are desktop (or client) and server Oss Current popular OSs include Windows 10, Server 2012/R2, Server 2016, Server 2019, UNIX/Linux, and macOS Mojave ©2021 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 26