Introduction to Operating Systems

• Education transcends mere fact memorization, it cultivates critical thinking
• The presentation covers an introduction to operating systems

Outline

• Definition of Operating System (OS)
• History of OS's
• Computer Hardware Architecture
• Types of Operating System
• Operating System Concept
• System Calls
• Hypervisor

Learning Outcomes

• Understanding the definition, importance, and main functions of an OS
• Differentiating between Kernel and User modes of operation
• Knowing key milestones in OS history
• Reviewing the architecture of computer hardware
• Identifying various OS types
• Grasping the core ideas and parts of an OS
• Defining System Calls
• Knowing the importance of System Calls
• Understanding the different kinds of System Calls, their applications, and functions
• Grasping the concept of virtualization

Definition of OS

• A diagram illustrates a computer system's organization
• Components include the CPU, disk controller, USB controller, and graphics adapter
• Peripherals like mouse, keyboard, printer, and monitor connect via these controllers to the memory

Role of OS

• An OS acts as the central point connecting applications with hardware
• Applications interact with the Monitor, Printer, Hard Drive, Keyboard and Mouse via the OS

Examples of OS

• Examples of Operating systems include: Windows, MacOS and Linux

Where the OS fits

• The OS resides between the hardware and software layers
• User mode includes web browsers, e-mail readers, and music players
• Kernel mode houses the operating system
• Software such as user interface programs exists between user mode and the OS
• The hardware is the foundation upon which the OS operates

Kernel Mode vs User Mode

• Kernel mode grants complete hardware access
• It allows the execution of any instruction the machine can perform, and is often called supervisor mode
• User mode limits available machine instructions, and it is the software's access

What is an OS?

• Operating Systems convert the ugly into the beautiful by providing a beautiful interface

OS and Abstraction

• The OS provides layers of abstraction
• Interacts by dealing with hardware to provide an interface to read and write disk blocks
• Programs can create, write, and read files without direct hardware interaction

What is an OS?

• The OS buffers output for the printer on the disk

Main Jobs of the OS

• Two main jobs include: providing abstractions to applications, and managing all the pieces of a complex system

History of OS's

The First Generation (1945-55): Vacuum Tubes

• Vacuum tubes and punched cards were used

Second Generation (1955-65): Transistors and Batch Systems

• During this era, transistors replaced vacuum tubes, leading to the development of batch systems and the FMS Fortran Monitor System

Third Generation (1965–1980): ICs and Multiprogramming

• Integrated circuits led to multiprogramming, IBM 360, SPOOLING (Simultaneous Peripheral Operation On Line) and computer time sharing

Minicomputers

• Bell Labs leads to Unix with Small PDP-7 Minicomputers

Fourth Generation (1980–Present): Personal Computers

• Large-scale integration (LSI) helped create Personal Computers

Windows Timeline

• MSDOS (1980)
• Windows 3.1 (1992)
• Windows XP (2001)
• Windows 7 (2009)
• Windows 10 (2015)
• Windows 1 (1985)
• Windows 95 (1995)
• Windows Vista (2007)
• Windows 8 (2012)
• Windows 11 (2021)
• GUI: Graphical User Interface

Macintosh Timeline

• 1984 Macintosh release
• 1999 Macintosh release
• 2001 Macintosh release
• 2017 Macintosh release
• GUI: Graphical User Interface

Unix History

• Unix versions and their derivatives are shown in a detailed architecture diagram

Fifth Generation (1990–Present): Mobile Computers

• The history and timeline of mobile phones

• Motorola 8900X-2

• Nokia 2146

• Nokia 3210

• Nokia 6210

• Ericsson T39

• Alcatel OT511

• Samsung E250

• Apple iPhone

• Blackberry Curve 8900

• Samsung Galaxy S2

• Samsung Galaxy S4

• Sony Xperia Z Ultra

• The Brick Phone was the First Mobile Phone from 1970

• The first real smart phone appeared in the mid -1990's: Nokia N900

• Ericsson released a smart phone in 1997 called The GS88 Penelope

Mobile Operating Systems

• iOS - Released by Apple in 2007
• Android - Released by Google in 2008

Computer Hardware Architecture

Simple Personal Computer Components

• Components include the monitor, keyboard, USB printer, and hard disk drive
• CPU and Memory are also key components
• Video controller, Keyboard controller, USB controller and Hard disk controller are important
• All components communicate through a bus

CPU

• CPU consists of fetching from memory, decode, type determination and execute

CPU Architecture

• The Central Processing Unit contains the control unit and arithmetic/logic unit
• Input and output devices communicate with the CPU via registers and memory
• Registers
• PC: Program Counter that contains the memory address of the next instruction to be fetched
• CIR: Current Instruction Register
• AC: Accumulator that stores intermediate ALU results

Multithreading

• Multi-core ships include Core 1, Core 2, Core 3 and Core 4

Memory

• Registers have the fastest access time and the least storage
• Cache is second fastest access time and more storage
• Main memory is slower access time and more storage
• Magnetic disk is very slow access time and highest storage
• Typical Memory Hierarchy:
• CPU > Registers (<1 KB)
• Cache (4 MB)
• Main memory (1-8 GB)
• Magnetic disk (1-4 TB)

Input/Output

• The OS interacts with I/O devices through device drivers and I/O controllers

Input Output Devices (I/O) and Methods

• The First Method consists of User Mode, Kernel Mode, Device Drive, Input and returning output
• The second method shows an interrupt controller
• The third method shows a DMA controller interacting with the CPU and Memory

Buses

• Buses link different components or devices to a computer
• CPU, ALU Registers and controls all communicate with memory and Input / Output via the system bus
• System Bus (Internal) consists of Data Bus, Address Bus, Control Bus

Basic Input Output System

• BIOS configurations, boot order, security and exit options

Types of Operating System

• Mainframe OS
• Server OS
• Multiprocessor OS
• Embedded OS
• Personal Computer OS
• Sensor Node OS
• Real Time OS
• Smart Cards OS

Operating System Concept

Core Components

• Processes
• Addresses Space
• File
• Protection
• Shell

Processes

• A program needs an executable program, program's data, resources, and synchronization to operate
• The virtual address space for processes must be contained

Process Communication

• Processes interact with resource-friendly, performance, and security, scalability
• Processes interact with interoperability, accessibility, and monitoability

Process Terminology

• PID (Process ID) is used to uniquely identify an active process
• UID (User IDentification) identifies users authorized to use the system
• GID identifies the groups to which users can belong

Address space

• 32 bits Address Space
• Stack
• Heap
• BSS
• Data
• Text
• 64 bits Address Space
• Reserved
• Stack
• Shared Libraries
• Reserved
• Heap
• Data
• Text

Address Space

• Virtual Memory Management handles memory map and RAM

Files

• Hierarchy of files including Root directory, Students, Faculty

I/O

• The operating system manages input/output operations through interfaces with keyboards, display terminals, and printers

Protection

• Protection includes access control and malware protection and information protection provided by the operating system

UNIX Example

• Describes file access control in a UNIX-like system using commands like ls (list files) and getfacl (get file access control list) to display permissions

Shell

• Shell interfaces with the Operating System and are mostly UNIX, such as Bourne Shell and C Shell

System Call

• Access to resources in kernel mode by a program running in user mode is achieved via a system call

System Call Sequence

• System call sequence for reading data from one file and copying to another with the following sequence:
• Source file> Writing a Prompt> Accept input> Writing a prompt> Accept input> Acquire input file> Acquire output file> open input file> create output file> Write to output file> Destination file> Read from Input file> close output file> Write completion message> Terminate completely

Types of System Calls

• System calls are categorized by function:Process Control, File Manipulation, Device Manipulation, Information Maintenance, and Communications

Hypervisor

• A hypervisor (Virtual Machines Monitor - VMM) which supports multiple guest VMS by virtually sharing its resources

Benefits of Hypervisor

• Speed - Hypervisor allows virtual machines to be created instantly
• Efficiency - Hypervisors allow for more efficient utilization of one physical server, with lower costs to run several virtual machines
• Flexibility - Hypervisors allow operating systems and their applications to run on a variety of hardware types by separating os from underyling hardware

Hypervisors

• Type 1 Hypervisor interacts directly with the physical server
• Type 2 Hypervisor interacts with the physical server through a host OS