Operating System Overview

• A computer system's digital computer hardware that is common to all computer system types is the focus
• Areas such as memory, CPU, data/address buses, cache, and pipeline are covered

Operating System Overview

• An operating system is needed because space is limited, queues are necessary for fairness, users can't go wherever without restrictions and security could be threatened by others,
• Systems without operating systems become inefficient and unworkable, descending into "CHAOS and ANARCHY"
• Modern computer systems have input/output devices, memory (primary storage), backing storage (secondary storage), and a CPU
• An operating system manages computer programs that range from games to planetary mission support

Tasks and Consequences of Unmanaged Systems

• Programs can read and write to any memory location in an unmanaged system, run non-stop, uses any printer at any time and save files anywhere on disks
• Unchecked priorities in unmanaged systems results in programs dominating forever or crashing the system

Operating System Responsibilities

• Operating Systems are responsible for managing the resources of a computer system
• By definition, an OS is the most critical and complex computer software
• An OS is intended as a protector of the democratic rights of computer programs
• With an Operating System, programs write only to designated memory, queue for execution, and save files to assigned disk spaces
• The operating system blocks unsafe actions
• An Operating System manages CPU time for running processes, memory allocation of processes and input/output events
• Operating systems also manage file structure on mass storage devices, system security, protection, and the command/user interface

Commercial Operating Systems

• Some commercial operating systems are MS Windows (workstations and servers), MS DOS (workstations) and Unix (servers and workstations)
• MCP (Unisys Master Control Program for mainframes) and VME (ICL Virtual Environment for Mainframes) are commercial operating systems
• Linux (servers and workstations), Symbian (handheld smart devices and PDAs) and Android (smartphones) are all commercial operating systems

Operating Systems Defined

• An Operating System (OS) is essential software
• It manages memory processes, software, and hardware, serving as a bridge between the user and the computer
• An operating system enables communication with a computer without needing to understand the computer's language
• Without an OS, a computer is ineffective

Operating System Operations

• Linking Users & Hardware, OS acts as the intermediary between the user and computer hardware
• Resource Allocation involves allocating memory, CPU time, and devices to different programs
• Process Control manages the execution of programs and the setting and executing of instructions
• Running Applications involves loading and running and supplying the necessary resources and services

Operating System Functions

• User Interface: The way users interact with the operating system, allowing input commands and receiving information
• File Management: How OSes handles the creation, organization, storage, retrieval, modification, and deletion of files
• Process Management: OS function responsible for creation, scheduling and termination of processes
• Device Management: How OSes manages input, output, and storage devices efficiently and correctly.
• Memory Management: How OSes handles controlling and allocating a computer's memory

User Interfaces

• GUI, most modern OSes use a Graphical User Interface like Windows and macOS, for easier interaction with icons, windows and buttons
• CLI, Command Line Interfaces, OS interaction via text-based commands

Input, Processing, Output

• Computer: Keyboard and mouse are the input, with the computer as the main processor and a display or printer as the output
• Problem: Numbers are the input (2 + 3), a formula is processed and creates a result as output (= 5)
• Human: Hearing and vision are the input, a brain process is used, and speech or body language is the output

Processes

• Various processes include power on/off, login, saving/opening files, printing, calculation and typing
• Additional processes include drawing a line, playing a song, connecting to the internet and sending an email

Process Management Details

• Process Management ensures the smooth execution and management of processes on a computer, covering creation, scheduling, and termination.
• Process Scheduling determines process order and CPU time allocation
• Multitasking allows systems to run multiple processes at once
• Context Switching is the OS's method of switching between processes and saving/restoring process states
• Synchronization & Communication ensures processes share resources/communicate in an orderly way

Memory Management

• Allocation assigns memory when a process starts whereas deallocation releases the memory once the process has ended
• Protection inhibits unauthorized memory access.
• Swapping moves a process to secondary storage, which makes memory available for other processes
• Paging organizes memory blocks in to frames, this allows for better memory usage

Computer Architecture

• Input devices range from keyboards, mouse, scanners, joystick
• CPUs have a Control Unit and Arithmetic Logic Unit (ALU)
• Output devices include monitors, printers, speakers and headphones

Device Management

• Device management is how operating systems ensure that input, output, and storage devices are used efficiently and correctly
• Input Devices: Keyboard, mouse, scanner are used to capture user input and store it in a buffer
• Output Devices: Monitor, printer, speaker are used to manage display and spooling for printers
• Storage Devices: HDD, SSD, USB, CD/DVD are used for storage allocation and file system management
• Communication Devices: Network adapter, bluetooth, modem are used to handles data transfer and protocol management

Device Drivers

• A device driver is a software program that regulates a hardware device, and allows the OS and the device to communicate
• A connected device prompts the OS to install the matching driver while communication sends commands to the device
• Execution translates commands into hardware instructions while the computer device sends feedback to the OS after completing the action

Device Drivers - Examples

• Printer uses HP Printer Driver, Epson Print Driver
• Graphics Card uses NVIDIA, AMD and Intel Graphics Driver
• Network Adapter uses Realtek and Broadcom Wifi Driver
• Sound Card uses Realtek HD Audio Driver
• USB Devices uses Generic USB Driver

File Management

• File management is all about creating, organizing, storing, retrieving, modifying, and deleting files on any given computer system
• The OS supplies a file system that can help users and applications can access the files

Functions of File Management

• File Creation & Deletion is an OS function that handles file creation and removal of files
• File Organization is a OS function that handles storing files in directories
• File Access Control is an OS function that manages file permissions
• File Reading & Writing is an OS function that handles file input and output activities
• File Security is an OS function that protects against unauthorized file access
• File Backup & Recovery is an OS function that prevents loss of file data
• File Systems is an OS function that organizes how files are stored

File System Structure

• A File System arranges data on drives with a hierarchical structure where files store data and directories organize files into groups
• File Paths refer to a file’s location in the system, as represented in Windows (C:\Users\Documents\report.docx) and Linux/macOS (/home/user/Documents/report.docx)

File Extensions

• File Extensions help to identify the file types and associated programs
• ".txt" is a text file, ".jpg" and ".png" are image files, ".mp3" and ".way" are audio file, ".mp4" and ".avi" are video file, ".exe" and ".app" are executable files

Types of File System

• FAT32 is used for Windows and USB drives but features simple, limited file size (4 GB)
• NTFS is used for Windows and supports large files, security, and journaling

Types of File Systems (continued)

• exFAT is used for Windows and macOS and works well for USB drives
• HFS+ is used for macOS devices and APFS is used for macOS and iOS devices, featuring fast optimization for SSDs
• ext3/ext4 is used for Linux and supports journaling

Common Operating Systems

• Desktop and Laptop Operating Systems are designed for personal computers (PCs) and workstations
• Mobile Operating Systems are designed for smartphones, tablets, and smart devices
• Server or Network Operating Systems are optimized for network management, security, and high-performance computing

Desktop and Laptop OS

• Windows is GUI-based (PC), user-friendly and best for general users and gaming
• macOS is used for Apple's personal computers and workstations (MacBook, iMac) and known for security and design
• GNU/Linux is personal, used Workstations, ISP, File, and print servers, and Three-tier client/servers. Also, used for programming and web services

Microsoft Windows

• Microsoft developed Windows and its first release was in 1985, with the latest version, being Windows 11
• Notable features include the GUI (Graphical User Interface), has wide hardware range, supports wide range of programs and the Microsoft store
• Windows use cases include office work, gaming, business apps and personal computing

MacOS

• Apple developed MacOS, with its first release being in 2001, with the latest version being Sonoma
• Notable features include a sleek and user-friendly GUI, is optimized for apple hardware and is exclusive, in it's security and Apple apps
• MacOS' use cases include creative work video editing, graphic design, professional business use, and software development

Linux

• An open-source community is responsible for Linux's development and is first release being in 1991
• Notable features include that's free and open-source, has high security and performance, customizable, and ideal for servers
• Example use cases including servers, cybersecurity, software development, and science

Mobile OSes

• Google Android: Google's OS for smartphones, tablets, and smartwatches based on Linux, known for customization,
• Apple iOS: Apple's OS for iPhones, iPads and iPods, known for security, smooth, premium experience, and tight integration
• Windows Phone: A discontinued Microsoft mobile OS that struggled to compete with Android and iOS, known for being innovative

Operating System Market Share

• Google Android has 70% market share globally with Android 14 (2024)
• Apple iOS as 25% market share globally with iOS 17 (2024)
• Windows Phone had 1-2% market share at its peak in 2010, now discontinued since 2017

Server or Network OS

• This specialized OS is designed to manage network resources and enable communication and data sharing between network devices
• The network OS gives devices, and allows for sharing of files, networked printers, and internet access on a network

Operating Systems - History

• First Generation (1945 - 55) were based on vacuum tubes, which were large slow to run, and consumed a lot of power
• The early hardware featured vacuum tubes in the memory circuits that used electromagnetic relays and Punched cards for storage
• First generation software was written via Machine/Assembly Language which input through punched cards and paper tape
• The ENIAC (Electronic Numerical Integrator and Computer) was the first fully electronic computer which was 100 ft long and used 17,000 vacuum tubes

First Generation Code & Calculations

• Programming was manually operated via plugboards or switches
• There were no high-level programming languages available, so every instruction was written in binary machine code or punch cards
• Programs ran machine hardware directly without the modern abstraction layer and could only run one program at a time

First Generation Resource Allocation

• Resource management such as CPU cycles, memory, and input/output device control were handled directly by the programs
• Operating systems didn't exist, so there wasn't an abstraction between the hardware and software in the code of first generation computers

Evolution of Languages

• Assembly language, which provides a symbolic representation of machine code, did not exist
• Early programmers had to write machine-level instructions directly, a process that was both slow and error-prone
• Languages Fortran and COBOL were not developed yet, so processes were specialized

Second Generation - Computers

• 1955-1965: Computers were used in many systems for transistors instead of vacuum tubes which resulted in being smaller, faster, and more reliable
• Key to second-generation systems was memory. Transistors were physically smaller, more reliable, and ran cooler than vacuum tubes
• This was faster than the first-generation core memory which served the main memory
• Magnetic tape tape and disks served as backup storage for higher computers
• Included higher-level languages in input and assembly for more accurate code

Generation Components - Punch Cards, Batching, Magnetic Tapes

• Punch Cards became the standard to input programs so people could work better with technology
• Batch Processing allowed jobs to run automatically, thus reducing human intervention
• Magnetic Tapes replaced punch cards to get better retrieval of data
• The precursors better management gave way to management complex systems

Third Generation Transition

• 1965-1980: Third generation computers became smaller, faster, and cheaper than their predecessors
• Integrated circuits (ICs) were used to make computers more efficient
• Large magnetic cores and tapes were used to handle processing and storage
• FORTAN, BASIC, Pascal, COBOL, and C were used to improve computing
• The 360 IBM, 370, and UNIC 1108 were used for faster processing

Multiprogramming and Beyond

• The third generation, a big update that allowed work on one task at a time that enhanced efficiency of the computers. Along with enhanced computing capabilities, came better user capabilities

Early Operating Systems

• There were operating system's that were key to shaping better features like time-sharing provided users with interactive access by allocating CPU time among tasks
• Also, integrated with buffer memory for input/output, eliminating the slow speeds and other issues

History of CP/M

• Gary Kildall, an American academic and programmer, worked at Intel and developed the first commercial operating system CP/M for 8-bit processor in 1974 which was written in PL/M
• Some features to look for include its ability to run on the Intel 8080 and Zilog z80
• 20KB of RAM is needed, which increases efficiency
• Command line interface (CLI) simple

1980 - The Present - GUI and Beyond

• From Apple Macintosh to Microsoft windows to make it more visually appealing
• Touch and voice interfaces enabled an intuitive experience for personal computing on smartphones
• Mobile OS like iOS and Android and tablets, with cloud computing and AI to be a key part

Computing

• Modern operating systems are enhancing their user experience and are increasing their usage through AI integration
• The real life and iOS are starting to add features of AR
• Computing to transform computing allows for faster tasks

Simulator

• Is a powerful tool that mimics hardware (CPU) and software (OS) layers of computer systems. By providing teaching functions
• Can examine the instruction and analyze programs

Software

• Can download three distinct parts to start software (CPU, Operating System, assembles)
• Provides most functions with process management
• Can create high and low level codes for different things

Simulation

• This is 5-stage and allows multiple instructions
• Is handled to increase ability

Simulators Details

• There's data and instruction cache, that the I cash to help speed process
• There are multiple processes simultaneously with fair CPUs
• Load programs to execute when told.