Operating Systems Overview

REVIEWER ON PLATFORM ●​ Operating systems ○​ Manage computer system hardware and software ○​ a program that acts as an intermediary between a user of a computer and the computer hardware ●​ Includes four essential subsystem managers ○​ Memory Manager ○​ Processor Manager ○​ Device Manager ○​ File Manager ●​ Network Manager ○​ Assumes responsibility for networking tasks ○​ Operating systems with networking capability ●​ User Command Interface ○​ Provides user communication ○​ User issues: Commands to the operating system ●​ Manager tasks ○​ Monitor its resources continuously ○​ Enforce policies determining: Who gets what, when, and how much ●​ Main Memory Management ○​ In charge of the main memory ○​ Random Access Memory ●​ Processor Management ○​ In charge of Allocating Central Processing Unit ○​ Tracks Process status ●​ Device Management ○​ In charge of monitoring all resources ●​ File Management ○​ In charge of tracking every file in the system ○​ Data files, program files, compilers, and application programs ●​ Cooperation Issues ○​ Essential manager ■​ Perform individual tasks and harmoniously interact with other managers ●​ Hardware: physical machine and electronic components ○​ Main memory (RAM) ■​ Data/Instruction storage and execution ○​ Input/Output devices (I/O devices) ■​ All peripheral devices in the system ■​ Printers, disk drives, CD/DVD drives, flash memory, and keyboards ○​ Central processing unit (CPU) ■​ Controls the interpretation and execution of instructions ■​ Controls the operation of the computer system ●​ Minicomputer ○​ Developed for smaller institutions ○​ Compared to the mainframe ●​ Supercomputer ○​ Developed for military operations and weather forecasting ●​ Microcomputer ○​ Developed for single users in the late 1970s ●​ Workstations ○​ Most powerful microcomputers ○​ Developed for commercial, educational, and government enterprises ●​ Servers ○​ Provide specialized services ●​ Types of Operating Systems ○​ Batch Systems ■​ Input relied on punched cards or tape ○​ Interactive Systems ■​ Faster turnaround than batch systems ○​ Real-time systems ■​ Reliability is key ■​ Fast and time limit sensitive. ●​ Hybrid systems ○​ Combination of batch and interactive ●​ Embedded systems ○​ Computers placed inside other products ●​ Threads ○​ Multiple actions are executed simultaneously ●​ Object-Oriented Design ○​ Driving force in system architecture improvements ●​ Kernel - Resides in memory at all times, performs essential tasks, and is protected by hardware ●​ Kernel reorganization - Memory resident: process scheduling and memory allocation. ●​ The Three Elements of an OS ○​ User Interface - The part of the OS that you interface with ○​ Kernel – The core of the OS. Interacts with the BIOS and the Operating System Types ○​ Multiuser – Two or more users work with the computer at the same time ○​ Multitasking - Two or more processes running at the same time. ○​ Multithreading - Two or more parts of the same process running at the same time. ●​ File System ○​ A File is a collection of bytes of information treated as a single unit. ●​ Windows Registered File Types ○​ A particular file extension can be Registered And Associated with a particular program. ●​ Storage Structure ○​ Main memory - only large storage media that the CPU can access directly ○​ Secondary storage – extension of main memory that provides large Nonvolatile storage capacity ○​ Hard Disk Drives - rigid metal or glass platters covered with magnetic recording material ○​ Non-volatile memory (NVM) devices– faster than hard disks,but volatile ■​ Mechanisms - determine how to do something. ■​ Policies - determine what will be done. ●​ Monolithic Structure - A common technique for designing operating systems where all of the functionality of the kernel is placed into a single, static binary file that runs in a single address space. ●​ Layered Approach - a layered approach, in which the operating system is broken into a number of layers (levels). The bottom layer (layer 0) is the hardware; the highest layer (layer N) is the user interface. ○​ Microkernels. The main function of the microkernel is to provide communication between the client program and the various services that are also running in userspace. ○​ Tracing - Collects data for a specific event, such as the steps involved in a system call invocation ○​ BCC (BPF Compiler Collection) is a rich toolkit that provides tracing features for Linux systems. BCC is a front-end interface to the eBPF (extended Berkeley Packet Filter) tool. ●​ IT Infrastructure: Hardware ○​ IT infrastructure: provides a platform for supporting all information systems in the business ○​ A firm’s IT infrastructure is composed of hardware, software, data management technology, networking technology, and technology services ●​ Moore’s Law - Moore’s Law predicts that the number of transistors fitting on a computer chip will double every one and a half to two years. ○​ Client/Server Computing ■​ Client's user point of entry ●​ The user generally interacts directly only with the client portion of the application, often to input data or retrieve data for further analysis. ●​ Servers- store and process shared data and perform network management activities ●​ A Storage Area Network (SAN) - SANs are an effort by corporations to reduce storage costs, manage information, increase flexibility, and provide near-certain backup. A typical SAN consists of a server, storage devices, and networking devices, and is used strictly for storage.