Operating System: Functions, Tasks & Process Management

• An operating system (OS) is the most important program for any computer system and digital device
• Without an OS, a computer is as useful as a piece of metal
• An OS was defined in the 1960s as "the software that controls the hardware"
• An OS allows other programs to run and make the hardware usable
• Nearly all computer use some kind of OS.
• OSs create the ability to serve purposes, interact with users, & adapt over time

Functions of an OS

• Control a network
• Access the Web
• Schedule jobs
• Configure devices
• Start the computer
• Provide a user interface
• Administer security
• Manage programs

Tasks of an Operating System

• Process management
• Memory management
• Storage management
• Device Management
• Protection and Security
• User Interface

Process Management

• A computer system includes OS processes that execute system files as well as user processes which execute user codes
• OS process management activities: -Controlling access to shared resources -Controlling application executions -Creating, executing, and deleting processes -Canceling or resuming processes -Scheduling processes -Synchronization -Communication -Deadlock handling for processes

Memory Management

• Programs must be mapped to absolute addresses and loaded into memory to be executed
• OS memory management allocates, frees, and re-allocates memory along with tracking memory usage

File Management

• File management provides a uniform logical view of information storage
• File management tasks: -Creating and deleting files and directories -Providing access to files -Allocating space for files -Backing up files -Securing files

Device Management

• The purpose of an OS is to abstract the specific hardware device peculiarities from the user.
• Tasks of device management: -Opening, closing, and writing device drivers -Communicating, controlling, and monitoring the device driver

Secondary Storage Management

• An OS manages secondary storage devices such as hard drives, solid-state drives, and external storage devices
• An OS manages secondary storage by organizing data, controlling access, and handling data transfers
• Secondary storage management also manages allocation of storage space, free space, and disk access scheduling.
• Secondary storage backs up the main memory, since main memory often can't permanently hold all data/programs

Protection and Security

• Protection is having computer controls and enforcement for regulating the access of programs, processes, or users to system resources
• The OS protects the resources of the system
• User authentication, file attributes, encryption, and data backups secure the system and provide basic protection

User Interface

• A user interface ensures consistent interaction between the user and computer
• The OS serves as the central point of interaction between user and computer

User Interface Types

• Command Line Interface (CLI)
• Menu-Based Interface
• Graphical User Interface (GUI)
• Voice-Based Interface
• Web-Based User Interface
• Touch Interface
• Point User Interface (PUI)
• Gesture Interface
• Touchless User Interface (TUI)
• Multimodal User Interface
• Holographic Interface

Command Line Interface (CLI)

• It allows for commands to be entered via the keyboard, and the program responds in a specific manner
• It takes text-based commands as inputs to perform computing tasks
• Has text-based input
• Mouse integration is sometimes disabled.
• No graphics can be seen on the screen
• Limited colors are used in its workspace

Menu-Based Interface

• A simple program user interface in which commands are performed through selections in a menu
• Typically, menus lead to further menus
• The screen may have an instruction followed by a numbered list of options
• Users may activate choices by typing a letter, pressing a direction key, or pointing with a mouse

Graphical User Interface (GUI)

• It is a type of interface that allows users to interact with electronic devices using visual indicators, with programs and commands represented via graphical forms such as icons
• GUI accepts point-and-click inputs via visual elements
• Microsoft Windows is a prime example of a GUI

Voice-Based Interface

• The concept of a handheld computer utilizing speech instead of keyboard or visual display
• Audio format stores information rather than text
• Information is accessed by issuing spoken commands instead of typin
• Feedback is aurally rather than visually provided

Types of Voice-Based Interfaces

• Speech Recognition Program
• Voice Recognition Program
• Voice and speech recognition are different things

Speech recognition Program

• It recognizes speech patterns and turns them into something else like commands or words on a screen
• For general dictation, transcribing, hand-free computer use, medical transcription, and automated customer service
• Supports accessiblity

Voice Recognition

• Identifies individuals based on their unique vocal characteristics
• Mac OS 9 had a feature where you could unlock your computer using your voice
• The computer knows it's you, but doesn't know what you’re saying
• It's like an audible fingerprint
• Designed for security

Web-Based User Interface

• Accepts input and provides output using web pages, which are transferred via the Internet and viewed through a web browser
• It allows users to interact with content or software on a remote server via a web browser
• Retrieved content from the web server can be interacted with in the web browser which acts as a client.

Touch Interface

• It's a graphical user interface on a combined input-output device, using a capacitive touchscreen
• Capacitive touchscreens use fingertip conductivity to register input
• Capacitive touchscreens are more responsive because pressure is unneeded

Point User Interface (PUI)

• Similar to a touch interface
• It uses a resistive touchscreen, another touchscreen type
• Pressure is needed from a fingertip to register input on resistive touchscreens

Resistive vs. Capacitive

• Touch interface uses a capacitive touch screen
• Point User Interface uses a resistive touch screen

Gesture Interface

• It recognizes gestures sketched with the user's hands or the use of a stylus, remote control, or mouse.
• Gestures come from bodily motion and interface with devices like computers, typically through hand movements

Touchless User Interface (TUI)

• An emerging technology related to gesture control
• Commands are performed with body motions without touching a keyboard, mouse, or screen
• Phones with "air gesture" are good examples; those features can open programs, access menus or even activate a button

Multimodal User Interface

• Supports the processing of two or more user input modalities (speech, pen, touch and multi-touch, gestures, gaze, virtual keyboard, etc.)
• Input modalities can coexist, used together, or switch off
• Input may include recognition-based technology e.g., speech, gesture as well as input like keyboard, touch, and sensor-based information

Holographic Interface

• It uses a projected image instead of a physical device for computer input
• Popular where complex inputs or many uses are required
• It utilizes holoprojectors construct, enabling scalable configurations

Types of Operating Systems

-Single tasking -Multitasking -Multi-use -Multiprocessing -Real time -Embedded

Single Tasking

• Single-tasking operating systems allow only one user to do one thing at a time -Palm OS for Palm PDAs is an example of a single user, single task OS
• If a user edits a document, they can't print at the same time. MS-DOS is an example of Single Tasking OS

Multitasking

• The type operating systems most people use on laptops and desktops
• Allows for more than one task or process to execute concurrently
• Examples include Windows platforms which let one user have several programs working together

Multi-User

• Allows many users to simultaneously make use of the computer's resources at the same time
• Computer networks use it and multiple users can access same applications and data at the same time
• Network OSs (NOS) such as Linux Server, UNIX, and new versions of Windows Server are multiuser OS examples

Multiprocessing OS

• Systems with have two or more processors for a single running process
• Processing tasks happen in parallel
• Each processor works on parts of a task or on other tasks.
• Multiple processors divide up the tasks, allowing faster computer calculations

Real-Time Operating System (RTOS)

• A type of OS designed to respond to an event within a predetermined time. Processing is done within a time constraint
• Used to control machinery, scientific instruments and industrial systems
• RTOS has a small user-interface capability with no end-user utilities since the system operates as a sealed box after delivery

Embedded OS

• An embedded operating system (OS) is already inside a device in the ROM
• Sometimes referred to as firmware
• The purpose of the embedded OS is to run code that allows the device to do its job
• They are used in appliances like microwaves, automatic washing machines, televisions, cameras and traffic control systems