Operating Systems Lecture Notes PDF

INTERNATIONAL & ACCESS FOUNDATION PROGRAMMES COMPUTER SCIENCE MODULE Semester I Part 8 Operating Systems Dr Nevan Bermingham Operating Systems... An operating system (OS) is a set of programs that manage computer hardware resources and provide com...

INTERNATIONAL & ACCESS FOUNDATION PROGRAMMES COMPUTER SCIENCE MODULE Semester I Part 8 Operating Systems Dr Nevan Bermingham Operating Systems... An operating system (OS) is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is a key piece of software on any computer system. Ordinarily, a user cannot run an application program on the computer without an operating system. Applications communicate with the operating system to access resources (e.g. memory, Operating Systems Why is an Operating System Important for Programmers & Systems Designers? Code is Compiled for an OS User Code Compiler Application Operating System Hardware Storag Input Networ Memor e Output k y Well Known Operating Systems OS Popularity Mobile & Desktop/Laptop OS Popularity – Super Computing Mobile OS Growth OS Popularity - Computing OS Popularity – Mobile & Windows Smartphones (52.61%) Desktops/Laptops (43.15%) Tablets (4.13%) OS Components Kernel Multitasking Program File System Execution Management Interrupts Device Drivers User Interface Networking (GUI) Memory Security Management OS Components  It is a bridge between Kernel Multitasking applications and the data processing done Program File System at the hardware level Execution Management  Provides the most basic level of control Interrupts Device Drivers over all of the computer's hardware User Interface devices. Networking  Determines which (GUI) programs get access to Memory which hardware Security Management resources  Manages memory access for programs in OS Components  An Kernel Multitasking application/program can interact with the Program File System hardware only by Execution Management obeying rules and procedures Interrupts Device Drivers programmed into the operating system. User Interface  Executing an Networking application program (GUI) involves the creation of Memory Security a process. Management  The operating system kernel assigns memory space and other OS Components  Provide an efficient Kernel Multitasking way for the operating system to interact with Program File System and react to its Execution Management environment.  An interrupt is a signal Interrupts Device Drivers from a process/application or User Interface hardware to do Networking something or pass (GUI) control. Memory  When an interrupt is Security Management received, the computer's hardware automatically suspends OS Components  UI is also called a Kernel Multitasking “shell”.  GUI:- Graphical User Program File System Interface, such as Execution Management MacOS and MS Windows. Interrupts Device Drivers  UI:- Command Line Interface (CLI), such User Interface as MS-DOS. Networking (GUI)  Acquire data from input hardware devices Memory Security (keyboard, mouse) and Management display prompts and status messages on output hardware OS Components  Responsible for Kernel Multitasking managing all system memory which is Program File System currently in use by Execution Management programs.  Ensures that a Interrupts Device Drivers program does not interfere with memory User Interface already in use by Networking another program. (GUI)  Memory protection Memory enables the kernel to Security Management limit each process' access to the computer's memory. OS Components  Multitasking refers to Kernel Multitasking the running of multiple independent programs Program File System on the same computer. Execution Management  Generally done via time-sharing (Kernel Interrupts Device Drivers Scheduler)  Control is passed to a User Interface process by the kernel, Networking (GUI) which allows the program access to the Memory CPU and memory. Security Management  Process Priority allows more or less resources/time OS Components  Access to data stored on Kernel Multitasking disks is a central feature of all operating systems Program File System  The specific way in Execution Management which files are stored on a disk is called a file Interrupts Device Drivers system, enabling files to have names and User Interface attributes. Networking  Allows (GUI) applications/user to Memory create, delete, open, Security Management and close files, as well as gather information about them (access OS Components  A device driver is a Kernel Multitasking specific type of computer software Program File System developed to allow Execution Management interaction with hardware devices Interrupts Device Drivers  Computers and their operating systems User Interface cannot be expected to Networking know how to control (GUI) every device, both now Memory Security and in the future. Management  The function of the device driver is to translate these OS Components  Computers running Kernel Multitasking dissimilar operating systems can participate Program File System in a common network Execution Management for sharing resources such as computing, files, Interrupts Device Drivers printers, and scanners using either wired or User Interface wireless connections. Networking  Networks essentially (GUI) allow a computer's Memory Security operating system to Management access the resources of a remote computer as if those resources were OS Components  Operating systems must Kernel Multitasking be capable of distinguishing between Program File System requests which should Execution Management be allowed to be processed, and others Interrupts Device Drivers which should not be processed.  Authentication of user User Interface Networking identity, such as a user (GUI) name, magnetic cards Memory or biometric data. Security Management  External security, internet or local network. Linux Distros  Create a chart that Research TASK: explains the key differences between MS Windows and the Linux Family of Operating System Architecture. Access to base code Run level Flavours or Variety Usability Licensing Support Command-line Updates Security Any Questions?