Computer Application.pdf

Computer Application First Stage By Ass. Lecturer Ahmed Mohammed Abdulkarem Operating System (OS) What is an operating system? An operating system (OS) is the program that, after being initially loaded into the computer by a boot program, manages all of the othe...

Computer Application First Stage By Ass. Lecturer Ahmed Mohammed Abdulkarem Operating System (OS) What is an operating system? An operating system (OS) is the program that, after being initially loaded into the computer by a boot program, manages all of the other application programs in a computer. The application programs make use of the operating system by making requests for services through a defined application program interface (API). In addition, users can interact directly with the operating system through a user interface, such as a command-line interface (CLI) or a graphical UI (GUI). Why use an operating system? An operating system brings powerful benefits to computer software and software development. Without an operating system, every application would need to include its own UI, as well as the comprehensive code needed to handle all low-level functionality of the underlying computer, such as disk storage, network interfaces and so on. Considering the vast array of underlying hardware available, this would vastly bloat the size of every application and make software development impractical. Instead, many common tasks, such as sending a network packet or displaying text on a standard output device, such as a display, can be offloaded to system software that serves as an intermediary between the applications and the hardware. The system software provides a consistent and repeatable way for applications to interact with the hardware without the applications needing to know any details about the hardware. As long as each application accesses the same resources and services in the same way, that system software -- the operating system -- can service almost any number of applications. This vastly reduces the amount of time and coding required to develop and debug an application, while ensuring that users can control, configure and manage the system hardware through a common and well-understood interface. Once installed, the operating system relies on a vast library of device drivers to tailor OS services to the specific hardware environment. Thus, every application may make a common call to a storage device, but the OS receives that call and uses the corresponding driver to translate the call into actions (commands) needed for the underlying hardware on that specific computer. Today, the operating system provides a comprehensive platform that identifies, configures and manages a range of hardware, including processors; memory devices and memory management; chipsets; storage; networking; port communication, such as Video Graphics Array (VGA), High-Definition Multimedia Interface (HDMI) and Universal Serial Bus (USB); and subsystem interfaces, such as Peripheral Component Interconnect Express (PCIe). What are the functions of an operating system? An operating system provides three essential capabilities: It offers a UI through a CLI or GUI; it launches and manages the application execution; and it identifies and exposes system hardware resources to those applications -- typically, through a standardized API. Every operating system requires a UI, enabling users and administrators to interact with the OS in order to set up, configure and even troubleshoot the operating system and its underlying hardware. There are two primary types of UI available: CLI and GUI. The CLI, or terminal mode window, provides a text-based interface where users rely on the traditional keyboard to enter specific commands, parameters and arguments related to specific tasks. The GUI, or desktop, provides a visual interface based on icons and symbols where users rely on gestures delivered by human interface devices, such as touchpads, touchscreens and mouse devices. The GUI is most frequently used by casual or end users that are primarily interested in manipulating files and applications, such as double-clicking a file icon to open the file in its default application. The CLI remains popular among advanced users and system administrators that must handle a series of highly granular and repetitive commands on a regular basis, such as creating and running scripts to set up new personal computers (PCs) for employees. Application management. An operating system handles the launch and management of every application. This typically supports an array of behaviors, including timesharing multiple processes, or threads, so that various tasks can share the available processors' time; handling interruptions that applications produce to gain a processor's immediate attention, ensuring there is enough memory to execute the application and its corresponding data without interfering with other processes; carrying out error handling that can gracefully remove an application's processes; and performing memory management without disrupting other applications or the OS. An operating system can also support APIs that enable applications to utilize OS and hardware functions without the need to know anything about the low-level OS or hardware state. As an example, a Windows API can enable a program to obtain input from a keyboard or mouse; create GUI elements, such as dialog windows and buttons; read and write files to a storage device; and more. Applications are almost always tailored to use the operating system on which the application intends to run. Additionally, an operating system can perform the following services for applications: In a multitasking operating system, where multiple programs can be running at the same time, the OS determines which applications should run in what order and how much time should be allowed for each application before giving another application a turn. It handles input/output (I/O) to and from attached hardware devices, such as hard disks, printers and dial-up ports. It sends messages to each application or interactive user -- or to a system operator -- about the status of operation and any errors that may have occurred. It can offload the management of batch jobs -- for example, printing -- so that the initiating application is freed from this work. On computers that can provide parallel processing, an operating system can manage how to divide the program so that it runs on more than one processor at a time. All major computer platforms (hardware and software) require, and sometimes include, an operating system, and operating systems must be developed with different features to meet the specific needs of various form factors. Device management. An operating system is responsible for identifying, configuring, and providing applications with common access to underlying computer hardware devices. As the OS recognizes and identifies hardware, the OS will install corresponding device drivers that enable the OS and applications running on the OS to use the devices without any specific knowledge of the hardware or devices. An operating system is responsible for identifying the correct printer and installing the appropriate printer drivers so that an application needs to only make calls to the printer without having to use codes or commands that are specific to that printer -- that is the operating system's job. The situation is similar for other devices, such as USB ports; networking ports; graphics devices, such as graphics processing units (GPUs); motherboard chipsets; and storage devices, such as Serial-Attached SCSI (SAS) disk adapters and disks that are formatted with a suitable file system. The OS identifies and configures physical and logical devices for service and typically records them in a standardized structure, such as Windows Registry. Device manufacturers periodically patch and update drivers, and the OS should update them to ensure best device performance and security. When devices are replaced, the OS also installs and configures new drivers. Operating system types and examples Although the fundamental roles of an operating system are widespread, there are countless operating systems that serve a wide range of hardware and user needs. General-purpose operating system. A general-purpose OS represents an array of operating systems intended to run a multitude of applications on a broad selection of hardware, enabling a user to run one or more applications or tasks simultaneously. A general-purpose OS can be installed on many different desktop and laptop models and run applications from accounting systems to databases to web browsers to games. General-purpose operating systems typically focus on process (thread) and hardware management to ensure that applications can reliably share the wide range of computing hardware present. Common desktop operating systems include the following:  Windows is Microsoft's flagship operating system, the standard for home and business computers. Introduced in 1985, the GUI-based OS has been released in many versions since then. The user-friendly Windows 95 was largely responsible for the rapid development of personal computing.  Mac OS is the operating system for Apple's Macintosh line of PCs and workstations.  Unix is a multiuser operating system designed for flexibility and adaptability. Originally developed in the 1970s, Unix was one of the first operating systems to be written in the C language.  Linux is a Unix-like operating system that was designed to provide PC users a free or low-cost alternative. Linux has a reputation as an efficient and fast-performing system. Mobile operating system: Mobile operating systems are designed to accommodate the unique needs of mobile computing and communication-centric devices, such as smartphones and tablets. Mobile devices typically offer limited computing resources compared to traditional PCs, and the OS must be scaled back in size and complexity in order to minimize its own resource use, while ensuring adequate resources for one or more applications running on the device. Mobile operating systems tend to emphasize efficient performance, user responsiveness and close attention to data handling tasks, such as supporting media streaming. Apple iOS and Google Android are examples of mobile operating systems. Embedded operating system: Not all computing devices are general purpose. A huge assortment of dedicated devices -- including home digital assistants, automated teller machines (ATMs), airplane systems, retail point of sale (POS) terminals and internet of things (IoT) devices -- includes computers that require an operating system. The principal difference is that the associated computing device only does one major thing, so the OS is highly stripped down and dedicated to both performance and resilience. The OS should run quickly, not crash, and handle all errors gracefully in order to continue operating in all circumstances. In most cases, the OS is provided on a chip that is incorporated into the actual device. A medical device used in a patient's life support equipment, for example, will employ an embedded OS that must run reliably in order to keep the patient alive. Embedded Linux is one example of an embedded OS. Network operating system: A network operating system (NOS) is another specialized OS intended to facilitate communication between devices operating on a local area network (LAN). A NOS provides the communication stack needed to understand network protocols in order to create, exchange and decompose network packets. Today, the concept of a specialized NOS is largely obsolete because other OS types largely handle network communication. Windows 10 and Windows Server 2019, for example, include comprehensive networking capabilities. The concept of a NOS is still used for some networking devices, such as routers, switches and firewalls, and manufacturers may employ proprietary NOSes, including Cisco Internetwork Operating System (IOS), RouterOS and ZyNOS. Real-time operating system: When a computing device must interact with the real world within constant and repeatable time constraints, the device manufacturer may choose to use a real-time operating system (RTOS). For example, an industrial control system may direct the operations of a sprawling factory or power plant. Such a facility will produce signals from myriad sensors and also send signals to operate valves, actuators, motors and countless other devices. In these situations, the industrial control system must respond quickly and predictably to changing real-world conditions -- otherwise, disaster may result. An RTOS must function without buffering, processing latencies and other delays, which are perfectly acceptable in other types of operating systems. Two examples of RTOSes include FreeRTOS and VxWorks. The differences between operating system types are not absolute, and some operating systems can share characteristics of others. For example, general-purpose operating systems routinely include the networking capabilities found in a traditional NOS. Similarly, an embedded operating system commonly includes attributes of an RTOS, while a mobile operating system can still typically run numerous apps simultaneously like other general- purpose operating systems.1 1 What is an Operating System (OS)? Definition, Types and Examples (techtarget.com) What is the difference between operating system and software application? Application software is a type of software that is designed to perform a specific task or set of tasks. It is developed using high-level programming languages such as Java, C, C++, etc. Examples of application software include Photoshop, VLC media player, Mozilla Firefox, Opera, Google Chrome, etc1 On the other hand, an operating system is a computer program that manages hardware and software resources and provides common services for computer programs. It works as an interface between the user and the hardware. The entire functionality of a computer system depends on the operating system. Examples of operating systems include Microsoft Windows, Linux, Unix, DOS, etc1 The following table summarizes the differences between application software and operating system:2 2 https://www.geeksforgeeks.org/difference-between-application-software-and-operating-system/ https://differencess.com/application-software-vs-operating-system-whats-the-difference/ https://pediaa.com/difference-between-operating-system-and-application-software/ https://short-fact.com/what-is-the-relationship-between-operating-system-and-application-software/ Basis of Application Software Operating System Comparison A system computer program that A computer program which is manages hardware and software Definition intended to perform some task resources and provides common classified along. services for computer programs. Application software is Operating system comes installed Installation downloaded from the internet. on the device purchased. Development It is developed by using virtual It is developed by using C++, C, Languages basic, C++, C, and Java. and assembly languages. The application software’s To manage hardware resources Goal primary goal is to accomplish a efficiently. specific task. Size It is usually in Megabytes (MB). It is usually in Gigabytes (GB). When the user turns on the The application is only launched computer, it begins to boot up and Functionality when the user wants it. continues to run until the user turns it off. It works as an interface between the user and hardware and It is built to perform some specific Usage performs a variety of tasks like tasks. memory management, scheduling, process management, etc. It always depends upon the operating system. But it does not Dependency depend upon application software. - It provides the path to execute or run the application software. It boots up when the user wants It runs when the user desires to Run Time and runs until the user switches run the application. off the machine.  Desktop The desktop is the primary user interface of a computer. When you boot up your computer, the desktop is displayed once the startup process is complete. It includes the desktop background (or wallpaper) and icons of files and folders you may have saved to the desktop. In Windows, the desktop includes a task bar, which is located at the bottom of the screen by default. In Mac OS X, the desktop includes a menu bar at the top of the screen and the Dock at the bottom. The desktop is visible on both Windows and Macintosh computers as long as an application or window is not filling up the entire screen. You can drag items to and from the desktop, just like a folder. Since the desktop is always present, items on the desktop can be accessed quickly, rather than requiring you to navigate through several directories. Therefore, it may be helpful to store commonly used files, folders, and application shortcuts on your desktop. Both the Windows and Macintosh operating systems allow you to customize the appearance of your desktop. In Windows 7, you can change the desktop background and select the default desktop icons within the "Personalization" control panel. In Mac OS X 10.6, you can change the desktop background using the "Desktop & Screen Saver" system preference. You can choose what items are shown on the desktop by selecting Finder → Preferences… and checking the items you want displayed.3 3 Desktop Definition - What is a computer's desktop? (techterms.com)  Computer Power Options Computer power options, also known as power settings or power plans, refer to the configurable settings that determine how a computer manages its power consumption and performance. These options allow users to control various aspects of power management to balance energy efficiency and system performance. Common power options include: 1. High Performance:  Maximizes system performance at the expense of increased power consumption.  Suitable for resource-intensive tasks like gaming or video editing. 2. Balanced (or Recommended):  Strikes a balance between performance and energy efficiency.  Suitable for everyday computing tasks and is often the default setting. 3. Power Saver (or Energy Saver):  Prioritizes energy efficiency by reducing system performance.  Suitable for tasks with lower processing demands, such as web browsing or word processing. 4. Custom Power Plans:  Allows users to create customized power plans with specific settings.  Users can adjust parameters like display brightness, sleep timeouts, and CPU power management. Key Power Options and Settings: 1. Sleep Mode:  Puts the computer into a low-power state, turning off the display and entering a low-energy state.  Allows for quick resumption of activity when the computer is awakened. 2. Hibernate:  Saves the current state of the system to the hard drive and shuts down the computer.  Resumes the system to its previous state when powered on again. 3. Display Settings:  Controls the time it takes for the display to turn off when the computer is inactive.  Adjusts display brightness to conserve energy. 4. Processor Power Management:  Controls the CPU's power state and performance.  Includes settings such as minimum and maximum processor state. 5. Hard Disk Power Management:  Controls the power state of hard drives to conserve energy.  Adjusts the time it takes for hard drives to enter a low-power state. 6. Wireless Adapter Settings:  Manages the power state of wireless network adapters.  Adjusts settings for optimized power consumption during periods of inactivity. How to Access Power Options: 1. Windows:  Go to "Control Panel" > "Power Options" (or "Settings" > "System" > "Power & sleep" in Windows 10/11). 2. macOS:  Navigate to "Apple menu" > "System Preferences" > "Energy Saver." 3. Linux:  Power management settings can vary based on the desktop environment (e.g., GNOME, KDE).  Settings are often accessible through the system settings or control panel. Configuring power options allows users to tailor their computer's behavior to their specific needs, whether they prioritize performance, energy efficiency, or a balance between the two. Adjusting these settings can contribute to longer battery life on laptops and reduced energy consumption on desktops.4 4 Windows 10 Power and Sleep Settings , Windows 10 Power Plans, How to Use Energy Saver Preferences on Your Mac, Power Management Guide for Ubuntu  Taskbar The taskbar is a major GUI element in Windows that spans the lower edge of the desktop. It helps users quickly switch between open windows and applications with a single click. The taskbar includes icons for every application running on the computer, as well as the Windows Start button (on the left side) and the system tray (on the right). Users may also pin icons to it to create shortcuts to applications they use frequently. The majority of the taskbar consists of a row of icons that represent both the application windows that are currently open and any other applications that you have chosen to pin to the taskbar. You can click a taskbar icon to launch that application, to bring its windows to the front, or to restore a minimized or hidden window. If an app has several windows open, clicking its taskbar icon will show thumbnails for each open window that you can choose from. You can click and drag icons on the taskbar to rearrange them. You can pin an application's icon to the taskbar while it is running by right-clicking it and selecting Pin to taskbar; you can remove an icon by right-clicking it and selecting Unpin from taskbar. The Windows taskbar has seen several changes since its introduction in Windows 95. Windows XP added taskbar grouping, which condensed windows from the same application into a single button on the taskbar. Windows 7 removed the text labels from taskbar buttons to save space and allowed you to pin apps to the taskbar directly (instead of to a separate Quick Launch toolbar). Windows 10 added a search field and the Task View button to the taskbar (next to the Start menu). Windows 11 changed the look of the taskbar even further by changing the default alignment from left-aligned to center-aligned. NOTE: Other operating systems include similar task switchers that allow users to switch between app windows. The macOS dock displays icons for open applications and pinned shortcuts, appearing as a floating element that adjusts its size as necessary. Several Linux desktop environments (like KDE Plasma and Unity) also use a taskbar-style application switcher on the bottom or side of the desktop.5 5 Taskbar Definition - What is the Windows taskbar? (techterms.com)  Hardware and software Hardware and software are the two essential components of a computer system. Without either of them, a computer would not be able to function properly. In this article, we will delve into the reasons why hardware and software are important in a computer system. Hardware refers to the physical components of a computer, such as the processor, memory, hard drive, monitor, keyboard, and mouse. These components are tangible and can be touched and seen. The hardware is responsible for the physical processes that occur in a computer. The processor, for example, is responsible for performing the calculations and logic operations that make software programs work. The memory stores data and instructions that the processor needs to access. The hard drive stores the operating system, applications, and user data. Software, on the other hand, refers to the programs and instructions that tell the hardware what to do. Software is intangible and cannot be seen or touched. It is a set of instructions that tell the computer what to do and how to do it. The operating system, for example, is a type of software that manages the computer’s resources and provides a user interface for interacting with the hardware. Now that we have defined hardware and software let’s examine why both are important in a computer system. Hardware is important because it provides the physical infrastructure that enables software to run. Without hardware, software would not be able to perform any functions. Hardware components such as the processor, memory, and hard drive are all critical to the performance of a computer. A powerful processor can handle more complex calculations and operations, while more memory allows for faster access to data and instructions. A larger hard drive can store more data and applications. Software is important because it provides the instructions that tell the hardware what to do. Without software, the hardware would be useless. Software provides the user interface for communicating with the hardware and allows users to perform tasks such as browsing the web, sending emails, or creating documents. The operating system is a crucial piece of software that manages the computer’s resources and provides a platform for other applications to run on. In summary, hardware and software are both essential components of a computer system. Hardware provides the physical infrastructure that enables software to run, while software provides the instructions that tell the hardware what to do. Without either of them, a computer would not be able to function properly. As technology continues to advance, both hardware and software will continue to play critical roles in the development of new and innovative computer systems.6 6 Why hardware and software are important in computer system | by dayaxwriter | Medium  software update A software update is a set of changes made to an existing software program, often released by the developer to address issues, improve performance, or add new features.7 Purposes:  Fixing bugs: Patches up errors or glitches that might cause problems in the software.  Enhancing security: Closes vulnerabilities that could be exploited by hackers or malware.  Improving performance: Optimizes the software to run faster, smoother, or use less resources.  Adding new features: Introduces new capabilities or expands existing ones. Types:  Minor updates: Usually address small bugs or security issues.  Major updates: Introduce significant changes or new features.  Security updates: Specifically focus on addressing vulnerabilities.  Critical updates: Fix urgent security flaws that could be exploited. 7 https://www.mail.com/blog/posts/software-security- updates/114/#:~:text=Keep%20devices%20and%20programs%20up,could%20offer%20entirely%20new%20features.  Benefits of updating:  Enhanced security: Protects your device and data from cyberthreats.  Improved stability: Reduces crashes and glitches for a smoother experience.  New features: Gives you access to the latest capabilities and improvements.  Better performance: Optimizes the software for faster and more efficient operation.  Compatibility: Ensures your software works well with other programs and devices. How to update:  Automatic updates: Many devices and programs offer automatic update options.  Manual updates: You can check for and install updates yourself. Common examples:  Operating system updates: For Windows, macOS, Android, iOS, etc.  Application updates: For web browsers, antivirus software, productivity apps, games, etc.  Device firmware updates: For routers, printers, smart home devices, etc. Remember: Keeping your software up-to-date is essential for maintaining security, stability, and optimal performance. Make it a regular habit to check for and install available updates. Security:  The state of being protected from harm or danger. In computing, this refers to protecting systems and data from unauthorized access, theft, damage, or disruption.8  Maintains confidentiality, integrity, and availability of information. Confidentiality ensures only authorized users can access data, integrity prevents data alteration, and availability guarantees access when needed.910  Implemented through various measures: Access control, encryption, firewalls, intrusion detection, penetration testing, secure coding practices, and more. 8 https://www.techtarget.com/searchsecurity/definition/cybersecurity#:~:text=Cybersecurity%20is%20the%20protec tion%20of,centers%20and%20other%20computerized%20systems. 9 https://www.ibm.com/topics/information- security#:~:text=Availability%20dictates%20that%20information%20security,known%20as%20%E2%80%9Cinformati on%20assurance.%E2%80%9D 10 https://www.techtarget.com/whatis/definition/Confidentiality-integrity-and-availability- CIA#:~:text=In%20this%20context%2C%20confidentiality%20is,that%20information%20by%20authorized%20people.  Bug:  An error or flaw in a computer program that causes it to malfunction. This can be anything from minor glitches to major crashes.  Not inherently related to security. A bug can simply affect the program's performance or functionality without posing any specific security risk.  However, bugs can become security vulnerabilities:  If a bug allows unauthorized access, data modification, or system disruption, it becomes a security vulnerability. This could be done unintentionally, but malicious actors can exploit these vulnerabilities to compromise systems and data.  Security bugs are critical and require prompt patching. Fixing them involves identifying the vulnerability, understanding its potential impact, and developing a secure patch to address it. Therefore:  All security vulnerabilities are bugs, but not all bugs are security vulnerabilities.  Identifying and fixing security bugs is a crucial aspect of cybersecurity. Here's an analogy:  Think of your house as a computer system. Security measures like locks, alarms, and strong doors protect it from intruders.  Bugs are like cracks in the walls or malfunctioning windows. They might not let thieves in directly, but they weaken the overall security and may be exploited.  Security bugs are like open windows or unlocked doors. They present immediate vulnerabilities that an intruder can exploit to gain access.  Software Ethics Software ethics is a branch of applied ethics that examines the ethical principles and problems that arise from the development, deployment, and use of software. It's essentially about making sure that the software we create is used for good and doesn't harm people or society. Here are some key aspects of software ethics:  Privacy: Protecting user data and ensuring users have control over how their information is collected and used.  Security: Ensuring software is secure from cyberattacks and that it doesn't introduce vulnerabilities that could be exploited.  Fairness and non-discrimination: Avoiding bias and discrimination in algorithms and software applications.  Accountability: Holding developers and companies accountable for the harms caused by their software.  Sustainability: Considering the environmental impact of software development and use.  Transparency: Being open and transparent about how software works and how it collects and uses data. Software ethics is becoming increasingly important as software becomes more pervasive in our lives. As software becomes more complex and powerful, the potential for harm also increases. Therefore, it's crucial to have a strong ethical framework to guide the development and use of software.11 Here are some examples of how software ethics can be applied in practice:  A developer should not create software that collects user data without the user's knowledge or consent.  A company should not use facial recognition technology in a way that discriminates against certain groups of people.  A government should not use software to spy on its citizens without a warrant.  By following ethical principles, software developers and companies can help to ensure that software is used for good and benefits everyone.  Here are some resources where you can learn more about software ethics:  The Association for Computing Machinery (ACM) Code of Ethics and Professional Conduct  The IEEE Code of Ethics12 11 https://pdh-pro.com/pe-resources/ethics-in-software- engineering/#:~:text=Ethics%20in%20software%20engineering%20is,the%20impact%20of%20unethical%20practices. 12 https://pdh-pro.com/pe-resources/ethics-in-software- engineering/#:~:text=Another%20cornerstone%20in%20the%20realm,conduct%20and%20decision%2Dmaking%20p rocesses.  The Software Engineering Body of Knowledge (SWEBOK)  File and Folder A file is an item that contains information, for example, text or images or music. When opened, a file can look very much like a text document or a picture that you might find on someone's desk or in a filing cabinet. On your computer, files are represented with icons, this makes it easy to recognize a type of file by looking at its icon. There are hidden files, Although you usually can't see a hidden file, it's an ordinary file in all other respects. You can choose whether a file is hidden or visible by changing its attribute feature of its properties to become hidden. If a file is hidden and you want to display it, you'll need to show all hidden files to see it. You can hide rarely used files to reduce clutter, but remember that hidden files still take up space on your hard disk. Although you can hide confidential files so other people can't see them, you shouldn't rely on hidden files as your only means of security or privacy. A folder is a container you can use to store files in. If you had thousands of paper files on your desk, it would be nearly impossible to find any particular file when you needed it. That's why people often store paper files in folders inside a filing cabinet. On your computer, folders work the same way. Here are some typical folder icons: Folders can also store other folders, a folder within a folder is usually called a subfolder. You can create any number of subfolders, and each can hold any number of files and additional subfolders.13 13 Babylon University What is a Recycle Bin? The Recycle Bin is a default folder found in computers running the Windows operating system. It acts as a temporary storage location for files and folders that have been deleted from the computer by mistake or purposefully. When you delete an item from the computer, it goes into the Recycle Bin instead of being permanently deleted. This allows users to recover accidentally deleted items without having to contact technical support or use data recovery software. How do I empty my Recycle Bin? To empty your Recycle Bin, right-click on it and select "Empty Recycle Bin" from the drop- down menu. This will permanently delete all of its contents and free up space on your hard drive. You can also select multiple items within the bin (or all of them) and click on "Delete" to remove them permanently. Be sure that you don't need any of these items before deleting them, as once they are gone, and there is no way to recover them without using third-party software or services.14 Computer Drives Disk drive (drive) – a computer device that stores and retrieves information, data, files, programs, etc., from a disk. The drive is often referred to by its letter (your drive letter may differ).15  A hard disk drive (hard disk or fixed disk) is usually designated as the “C: drive”. The hard disk drive is the main data storage hardware device in a computer that can provide quick access to large amounts of data. 14 https://www.lenovo.com/ph/en/glossary/recycle-bin/?orgRef=https%253A%252F%252Fwww.google.com%252F 15 https://opentextbc.ca/computerstudies/chapter/types-of-computer-drives-and-pointing-actions/  A CD/DVD drive is usually designated as the “D: or G: drive”.  A removable disk (USB) is usually designated as the “H: drive” or “K: drive”. o A USB flash drive is a small portable external device used for data storage. o The most common use for external drives (USB) is for backup purposes or to transfer files from one computer to another.  Types of computer Two types of classification: - On the basis of Technology. - On the basis of Size Types of computers on the basis of Technology: - Analog Computers. - Digital Computers. - Hybrid Computers. Analog Computer is a computing device that works on continuous range of values. The results given by the analog computers will only be approximate since they deal with quantities that vary continuously. It generally deals with physical variables such as voltage, pressure, temperature, speed, etc. A digital computer operates on digital data such as numbers. It uses binary number system in which there are only two digits 0 and 1. Each one is called a bit. The digital computer is designed using digital circuits in which there are two levels for an input or output signal. These two levels are known as logic 0 and logic 1. Digital Computers can give more accurate and faster results. Based on the purpose, Digital computers can be further classified as: General Purpose Computers Special Purpose Computers A hybrid computer combines the desirable features of analog and digital computers. It is mostly used for automatic operations of complicated physical processes and machines. Now- a-days analog-to-digital and digital-toanalog converters are used for transforming the data into suitable form for either type of computation. For example, in hospital’s ICU, analog devices might measure the patients temperature, blood pressure and other vital signs. Types of computers on the basis of size Super Computers Mainframe Computers Mini Computers Micro Computers Super Computers : When we talk about types of computers, the first type that comes to our mind would be Super computers. They are the best in terms of processing capacity and also the most expensive ones. These computers can process billions of instructions per second. Normally, they will be used for applications which require intensive numerical computations such as stock analysis, weather forecasting. Mainframe Computers : Mainframe computers can also process data at very high speeds i.e., hundreds of million instructions per second and they are also quite expensive. Normally, they are used in banking, airlines and railways etc. for their applications. Mini Computers : are lower to mainframe computers in terms of speed and storage capacity. They are also less expensive than mainframe computers. Some of the features of mainframes will not be available in mini computers. Hence, their performance also will be less than that of mainframe computers. Mini Computers Desktop Computers Laptop Computers Handheld Computers Desktop Computers : Today the Desktop computers are the most popular computer systems. These desktop computers are also known as personal computers or simply PCs. They are usually easier to use and more affordable. They are normally intended for individual users for their word processing and other small application requirements. Laptop Computers : Laptop computers are portable computers. They are lightweight computers with a thin screen. They are also called as notebook computers because of their small size. They can operate on batteries and hence are very popular with travelers. The screen folds down onto the keyboard when not in use. Handheld Computers or Personal Digital Assistants (PDAs) : Handheld computers or Personal Digital Assistants (PDAs) are pen-based and also battery powered. They are small and can be carried anywhere. They use a pen like stylus and accept handwritten input directly on the screen. They are not as powerful as desktops or laptops but they are used for scheduling appointments, storing addresses and playing games. They have touch screens which we use with a finger or a stylus.  Computer A microprocessor is a central processing unit (CPU) that serves as the brain of a computer or electronic device. It is an integrated circuit that performs arithmetic and logic operations, controls input and output devices, and executes instructions from memory. 16 A microprocessor consists of an ALU, control unit and register array. Where ALU performs arithmetic and logical operations on the data received from an input device or memory. Control unit controls the instructions and flow of data within the computer. Memory is most often referred to as the primary storage on a computer, such as RAM. Memory is also where information is processed. It enables users to access data that is stored for a short time. The data is only stored for a short time because primary memory is volatile, meaning it isn't retained when the computer is turned off. 16 https://www.educative.io/answers/what-is-a-microprocessor The term storage refers to secondary memory and is where data in a computer is kept. An example of storage is a hard drive or a hard disk drive (HDD). Storage is nonvolatile, meaning the information is still there after the computer is turned off and then back on. A running program may be in a computer's primary memory when in use -- for fast retrieval of information -- but when that program is closed, it resides in secondary memory or storage. How does computer memory work? When a program is open, it is loaded from secondary memory to primary memory. Because there are different types of memory and storage, an example of this could be a program being moved from a solid-state drive (SSD) to RAM. Because primary storage is accessed faster, the opened program will be able to communicate with the computer's processor at quicker speeds. The primary memory can be accessed immediately from temporary memory slots or other storage locations. Memory is volatile, which means that data in memory is stored temporarily. Once a computing device is turned off, data stored in volatile memory will automatically be deleted. When a file is saved, it will be sent to secondary memory for storage. Types of computer memory17 In general, memory can be divided into primary and secondary memory; moreover, there are numerous types of memory when discussing just primary memory. Some types of primary memory include the following Cache memory: is a special very high-speed memory. The cache is a smaller and faster memory that stores copies of the data from frequently used main memory locations. There are various different independent caches in a CPU, which store instructions and data. The most important use of cache memory is that it is used to reduce the average time to access data from the main memory.18 Characteristics of Cache Memory:  Cache memory is an extremely fast memory type that acts as a buffer between RAM and the CPU.  Cache Memory holds frequently requested data and instructions so that they are immediately available to the CPU when needed. 17 https://www.techtarget.com/whatis/definition/memory 18 https://www.geeksforgeeks.org/cache-memory-in-computer-organization/  RAM: The term is based on the fact that any storage location can be accessed directly by the processor. Two types of RAM , Dynamic RAM. DRAM , Static RAM. SRAM. Read-only memory: ROM is a type of computer storage containing nonvolatile, permanent data that, normally, can only be read and not written to. ROM contains the programming that enables a computer to start up or regenerate each time it is turned on. Virtual memory: Virtual memory is a memory management technique where secondary memory can be used as if it were a part of the main memory. Virtual memory is a common technique used in a computer's operating system (OS). Virtual memory uses both hardware and software to enable a computer to compensate for physical memory shortages, temporarily transferring data from random access memory (RAM) to disk storage. Mapping chunks of memory to disk files enables a computer to treat secondary memory as though it were main memory. Today, most personal computers (PCs) come with at least 8 GB (gigabytes) of RAM. But, sometimes, this is not enough to run several programs at one time. This is where virtual memory comes in. Virtual memory frees up RAM by swapping data that has not been used recently over to a storage device, such as a hard drive or solid-state drive (SSD).19 19 https://www.techtarget.com/searchstorage/definition/virtual-memory Virtual memory is important for improving system performance, multitasking and using large programs.  Computer Input and Output Devices20 The functioning of a computer system is based on the combined usage of both input and output devices. Using an input device we can give instructions to the computer to perform an action and the device reverts to our action through an output device. Input Device Definition: A piece of equipment/hardware which helps us enter data into a computer is called an input device. For example keyboard, mouse, etc. Output Device Definition: A piece of equipment/hardware which gives out the result of the entered input, once it is processed (i.e. converts data from machine language to a human- understandable language), is called an output device. For example printer, monitor, etc. List of Input Devices 1. Keyboard 2. Mouse 3. Joy Stick 4. Light Pen 5. Microphone 6. Scanner 7. Barcode Reader 20 https://byjus.com/govt-exams/input-output-devices/ List of Output Device 1. Monitor 2. Printer 3. Speakers 4. Projector 5. Headphones  Main Screen – Common Features A Ribbon refers to a graphical control element in the form of a set of toolbars placed on several tabs. It is often found in applications like Microsoft Office products (Word, Excel, PowerPoint), where it provides a tabbed toolbar with various commands and options related to document creation and editing. The ribbon organizes functions into a series of tabs, making it easier for users to access features. A Tab is a user interface element that organizes content into separate sections. Users can switch between these sections by clicking on different tabs. This is commonly seen in dialog boxes, settings menus, and various application interfaces. A Status Bar is a graphical element in a user interface that provides information about the current status or state of a system, application, or process. It is typically located at the bottom of a window or screen, although its placement can vary depending on the design of the user interface. The status bar may contain various indicators, icons, or textual information to convey important details to the user. Tabs: 1. Organization:  Tabs organize content: Tabs are used to group related content or functionalities within a single window. Each tab represents a distinct section or view. 2. Navigation:  Switching between views: Users can switch between different views or sections by clicking on the respective tab. This provides a convenient way to navigate within the same window. 3. Content Display:  Separate content areas: Each tab typically has its content area, allowing the presentation of different information, settings, or tasks without cluttering the interface.  4. Contextual Information:  Contextual relevance: Tabs are often used when different sets of information or functionalities are relevant in different contexts. For example, tabs in a web browser might represent different open web pages. 5. Examples:  Web Browsers: Tabs are commonly used to represent multiple open web pages.  Software Applications: Tabs in software applications (e.g., text editors, IDEs) represent different documents or project views. Status Bar: 1. Information Display:  Status information: The status bar is a dedicated area for displaying information about the current status or state of the system, application, or process. 2. System Indicators:  System-related indicators: It often includes icons or indicators for system- related information, such as network connectivity, battery status, volume level, or notifications. 3. Progress Indicators:  Progress feedback: Progress bars or indicators may be included in the status bar to inform users about the progress of ongoing tasks, like file downloads or uploads. 4. Messages and Notifications:  Status messages: The status bar may display brief messages or notifications to provide feedback on completed tasks, errors, or other important events. 5. User Controls:  Quick settings: Some status bars include shortcuts or quick access buttons for common settings, allowing users to toggle features like Wi-Fi, Bluetooth, or screen brightness.  Basic definition and concepts in MS office Microsoft Office is a suite of productivity applications developed by Microsoft. These applications are commonly used in many industries and offices around the world. Here are some basic definitions and concepts in MS Office: Microsoft Word: This is a word processing software used for creating and editing documents. It provides a range of features like formatting text, adding images, creating tables, and more. Microsoft Excel: This is a spreadsheet program used for data analysis, calculations, and visualization. Excel allows users to create and manipulate spreadsheets with formulas, functions, and charts. Microsoft PowerPoint: This is a presentation software used for creating slide-show presentations. It allows users to add text, images, videos, and animations to convey information effectively. Microsoft Outlook: This is an email client and personal information management program. Outlook allows users to send and receive emails, manage calendars, schedules, contacts, and tasks. Microsoft Access: This is a database management system used for storing and retrieving large sets of data. Access provides tools for creating forms, queries, reports, and connecting tables to build efficient database systems. Microsoft OneNote: This is a note-taking program that allows users to gather, organize, and share notes, drawings, and multimedia content in a digital notebook format. These applications are designed to work together, allowing users to integrate and share data between different programs. MS Office also provides features like collaboration, document sharing, templates, and advanced formatting options to enhance productivity and efficiency in the workplace.21 21 Microsoft Office Support , Microsoft Office Training Center  Control Panel The Control Panel in Windows is a centralized hub that provides access to various system settings and administrative tools. It allows users to customize and manage different aspects of their computer. The Control Panel is organized into categories, with each category containing related settings. As of my knowledge cutoff in January 2022, here are some common categories you may find in the Windows Control Panel: Common Control Panel Categories: 1. System and Security:  Security and Maintenance: Configure security settings and view system maintenance information.  System: Access system information, change computer name, and manage system settings.  Power Options: Adjust power settings and create power plans. 2. Network and Internet:  Network and Sharing Center: View network status, set up new connections, and troubleshoot network issues.  Internet Options: Configure web browser settings and security options. 3. Hardware and Sound:  Devices and Printers: Manage connected devices and printers.  Sound: Adjust audio settings and manage playback devices. 4. Programs:  Programs and Features: Uninstall or change programs installed on the computer.  Default Programs: Set default programs for various file types and protocols. 5. Ease of Access:  Ease of Access Center: Access accessibility options and settings.  Speech Recognition: Set up and configure speech recognition features. 6. Appearance and Personalization:  Personalization: Customize desktop background, colors, and themes.  Display: Adjust screen resolution and orientation.  Folder Options: Configure how folders and files are displayed. 7. Clock and Region:  Date and Time: Set the system date and time.  Region and Language: Configure regional settings and language options. 8. User Accounts:  User Accounts: Manage user accounts, change account settings, and create new accounts. 9. Windows Update:  Windows Update: Check for and install Windows updates. 10.Administrative Tools:  Task Scheduler: Schedule tasks to run automatically.  Event Viewer: View detailed information about system events and errors.  Computer Management: Access various system management tools. Accessing the Control Panel:  In Windows 10 and Windows 11, you can access the Control Panel through the Start menu by searching for "Control Panel."  In earlier versions of Windows, you can access it through the Start menu or by right- clicking on the Computer (or This PC) icon on the desktop and selecting "Properties."