Is114 Concepts PDF

is114 concepts Single computer Software relies on hardware to function; it sends instructions to hardware components which then carry out tasks. When you type a document in Microsoft Word (application software), the CPU processes your keystrokes (hardware) to display...

is114 concepts Single computer Software relies on hardware to function; it sends instructions to hardware components which then carry out tasks. When you type a document in Microsoft Word (application software), the CPU processes your keystrokes (hardware) to display text on your monitor (output device). Data Processing Process. Data Request: When an application needs data (e.g., opening a file), it sends a request to the operating system.. Operating System: The OS locates the data on the storage device and retrieves it.. Transfer to RAM: The data is then loaded from the storage device (like an HDD or SSD) into RAM. This is done because RAM is much faster than storage, allowing for quick access by the CPU.. Processing by CPU: Once the data is in RAM, the CPU can access it quickly and perform the necessary computations or operations.. Output: After processing, the results can be sent back to RAM for further use or directly to output devices (like a monitor or printer). Hardware Definition: Hardware refers to the tangible, physical components of a computer system that can be seen and touched. 5 It includes all the machinery and equipment that make up a computer. 4 Central Processing Unit (CPU) 3 Definition: The CPU, often called the brain of the computer, is responsible for executing instructions and processing data. 2 Function: It carries out all the commands from software applications 1 by performing calculations and managing data flow. Components: ○ Cores: Modern CPUs have multiple cores, which allow them to process several instructions simultaneously, improving performance. ○ Clock Speed: Clock speed indicates how many instructions a CPU can execute in one second. ◆ Higher clock speeds mean faster processing.  ◆ Measured in Hertz (Hz) Primary Memory Definition: Also known as RAM (Random Access Memory), primary memory is where the computer temporarily stores data that is actively being used or processed. Function: It allows quick access to data for the CPU, enabling smooth operation of applications and tasks. Characteristics: ○ Volatile Memory: Data in primary memory is lost when the computer is turned off, unlike secondary storage (like hard drives) where data is saved permanently. Secondary Memory Definition: This refers to long-term storage devices that retain data even when the computer is powered off. Function: It stores data permanently, such as files, applications, and the operating system. Characteristics: Non-volatile: Data remains intact even without power. Slower than primary memory: Accessing data takes more time compared to primary memory. Feature Primary Memory Secondary Memory (RAM) Type Volatile Non-volatile Purpose Temporary storage for Permanent storage for active tasks data Speed Fast Slower Data Retention Loses data when Retains data without powered off power Examples RAM Hard drives, SSDs, USB drives Organisation of Files and Folders in a Computer Files and folders are organized in a hierarchical structure within a computer's file system. This structure resembles a tree, where: Root Directory: The top-level directory from which all other folders and  files branch out. (/) Folders (Directories): Containers that hold files or other folders. They help organize related files together. Files: Individual units of data stored on the computer, such as documents, images, or applications. Navigating a Filesystem We can navigate a filesystem using two interfaces: Graphical user interface (GUI) Command line interface (CLI): Linux Datacamp commands Feature Absolute Path Relative Path Definition Complete path from Path relative to current root directory Starting Point Begins at root Begins at current directory working directory Example C: Documents/file.txt \Users\Username\Doc uments\file.txt Usage Unambiguous, always Flexible, can change points to same based on context location Process Definition: A process is an instance of a program that is currently being executed by the computer. It includes the program code and its current activity, such as the values of variables, the program counter, and the state of the process. Examples: When you open Microsoft Word, the instance of that program running in memory is a process. Program Definition: A program is a set of instructions written in a programming language that tells a computer how to perform specific tasks. It is essentially a static file stored on a storage device (like a hard drive or SSD). Feature Program Process Definition A set of instructions An active instance of a stored on disk program in execution State Static Dynamic Resource Usage Does not use system Actively uses CPU and resources until memory  Feature Program Process Definition A set of instructions An active instance of a stored on disk program in execution State Static Dynamic Resource Usage Does not use system Actively uses CPU and resources until memory executed Examples Microsoft Word file The running instance (.exe) of Microsoft Word In summary, a program is a passive collection of instructions stored on disk, while a process is an active execution of those instructions, utilizing system resources. Software Definition: Software refers to the intangible instructions that tell hardware how to perform specific tasks. It consists of programs and applications that run on computers. Application Software Definition: Application software consists of programs designed to perform specific tasks for users. These tasks can range from productivity to entertainment. Functions: ○ Task-Oriented: Applications are built to help users accomplish particular functions, such as word processing, spreadsheet calculations, or graphic design. ○ User Interaction: They provide interfaces for users to interact with the software directly, often through buttons, menus, and forms. ○ Utilization of OS Services: Applications rely on the operating system to manage hardware interactions. For example, when saving a document, an application requests the OS to handle the file storage process. Operating System (OS) Definition: The operating system is a foundational software that manages the computer's hardware and software resources. It acts as an intermediary between users and the computer hardware. Functions: ○ Resource Management: The OS allocates resources such as CPU time, memory space, and input/output devices to various applications, ensuring they operate efficiently without conflicts. ○ Data Organization: It organizes files and directories on storage  ○ devices, allowing users and applications to access data easily. ○ User Interface: The OS provides a user interface (UI), which can be graphical (GUI) or text-based (CLI), enabling users to interact with the computer. ○ System Services: It offers various services like file management, process scheduling, and security features that applications can utilize. Feature Operating System Application Software Purpose Manages hardware Performs specific and software tasks for users resources Interaction with Directly interacts with Relies on OS for Hardware hardware hardware access User Interface Provides a UI for user Offers task-specific interaction interfaces Examples Windows, macOS, Microsoft Word, Linux Instagram Network of Computers Definition: A network is a collection of interconnected devices that communicate with each other to share resources, information, and services. Networks can vary in size and complexity, ranging from small local networks (like a home Wi-Fi network) to vast global networks (like the Internet). Networking Protocols Definition: Protocols are standardised rules that dictate how data is transmitted over networks. They ensure that devices can communicate effectively despite differences in hardware and software. Examples: ○ TCP/IP (Transmission Control Protocol/Internet Protocol): The fundamental suite of protocols for the Internet that ensures reliable data transmission. ◆ In IS114 cheatsheet ○ HTTP (HyperText Transfer Protocol): Used for transferring web pages. TCP/IP Stack Application layer (data) Used by applications  http, ssh, https protocol Transport layer (port number) Checks data size (i.e. data is too big) ○ If data is too big, separates data into smaller pieces and sends each piece separately. ○ When receiver receives each packet, it assembles the data together. specifies port number TCP, UDP protocol Internet layer (IP address) assigns an IP address - ensures data can be transmitted to the correct destination within a short time ○ source IP ○ destination IP IP protocol Link layer (MAC address) how data is transmitted from previous hub to the next hub ○ uses mac address to transfer message from previous hub to next hub ethernet protocol ○ IEEE 802.3 (wired Ethernet) ○ IEEE 802.11 (wireless Ethernet; Wi-Fi) ○ SONET/SDH (fibreoptic communication) ○ 4G, 5G (Cellular) ◆ PPP (Point-to-Point protocol for direct router-to-router communication) Internet Definition: The Internet is a vast global network that connects millions of private, public, academic, business, and government networks. It allows computers to communicate and share resources, enabling activities such as browsing websites, sending emails, and streaming videos. Key Features: ○ Interconnectedness: Devices from different locations can communicate seamlessly. ○ Resource Sharing: Users can access shared files, applications, and services. The World Wide Web (WWW) Definition: The World Wide Web is a system of interlinked hypertext documents accessed via the Internet using web browsers. It allows users to navigate from one page to another through hyperlinks. Websites are made up of HTML documents that are served by web servers, using the Client-Server model. When a user requests a website: ○ The browser sends an HTTP request to the server hosting that site. ○ The server responds by sending back the HTML content. ○ The browser renders this HTML content for user interaction. Websites can be hosted on different types of servers: ○ Local Servers: Host websites on personal or organizational hardware. ○ Cloud Services: Use remote servers managed by third-party providers for scalability and flexibility. ○ Public accessibility is achieved through domain names (e.g., www.example.com) linked to IP addresses. Client-Server Model Not a protocol! Definition: The client-server model is an architectural framework where clients (devices or applications) request resources or services from servers (powerful systems that provide resources). Components ○ Client: Typically a user device or application that initiates requests for resources (e.g., a web browser requesting a webpage). ○ Server: A system that processes requests from clients and provides the requested resources or services (e.g., a web server hosting websites). Request/Response Cycle: This cycle describes how clients interact with servers:. The client sends a request to the server using a specific protocol (e.g., HTTP).. The server processes the request and retrieves the necessary data.. The server sends back a response to the client, which may include the requested data (like a webpage). Addressing Definition: Addressing involves assigning unique identifiers to devices on a network so they can locate and communicate with each other. This is primarily done through IP addresses. Types of IP Addresses: ○ IPv4: A 32-bit address format (e.g., 192.168.1.1). ○ IPv6: A newer 128-bit address format designed to accommodate the growing number of devices on the Internet. Process: ○ Router (ISP - internet service provider) assigns private IP address to each computer (DHCP) ○ IP address is sent in addition to content being sent out to the Internet ○ Data/content is sent to router from computer before being sent out to internet ○ Default gateway: default IP address computer sends messages to ○ Network address translator (NAT): router (ISP) will translate private IP address to public IP address or vice versa ◆ Router improves security cloud computing ssh protocol: helps to monitor http requests and responses iaas: renting the machine for use in cloud virtualization: using a small virtual computer within a big computer network