Chapter 2 - Hardware and Software PDF

Hardware And Software CHAPTER 2 Contents: 2.1 Mainframe computers and supercomputers 2.2 System software 2.3 Utility software 2.4 Custom-written software and off-the-shelf software 2.5 User interfaces Introduction – Mainframe Computers: Primary Use: ◦ Used by large organizations for bulk da...

Hardware And Software CHAPTER 2 Contents: 2.1 Mainframe computers and supercomputers 2.2 System software 2.3 Utility software 2.4 Custom-written software and off-the-shelf software 2.5 User interfaces Introduction – Mainframe Computers: Primary Use: ◦ Used by large organizations for bulk data-processing applications such as censuses, statistics, and transaction processing. Characteristics: ◦ Larger, more processing power, and costlier than personal computers or laptops. The IBM z15 with up to 190 core ◦ Prices in 2020 started at $75,000. ◦ Modern mainframes are the size of a large cupboard, reduced significantly from their room-sized predecessors (1950–1990). Functionality: ◦ Multitasking and multi-user systems allow many people to work on different problems simultaneously. ◦ Equipped with hundreds of processor cores for efficient parallel processing (opposite of Serial processing) of numerous small tasks. ◦ Highly reliable, resistant to viruses and Trojan horses. Coexistence with PCs: ◦ Organizations often use mainframes alongside PCs and laptops. ◦ PCs now feature multi-core processors (up to 18 cores) for parallel processing, but mainframes still offer superior multitasking capabilities. Introduction – supercomputers: Performance: ◦ Can have over 100,000 processing cores. ◦ Perform calculations at an exponentially faster rate than mainframes or PCs. Example: ◦ The Summit supercomputer (launched in 2018 in USA), can perform in 1 second what would take the world population 305 days to achieve at one calculation per second per person. Cray XC40 supercomputer, which can have up to 172000 processor cores ◦Occupies a space equivalent to two tennis courts. Applications: ◦ Ideal for processing large-scale data tasks, such as payroll batch processing for hundreds of workers in seconds. Comparison Summary Supercomputers Mainframe computers Purpose: Designed for maximum Purpose: Built for reliability, computational speed to handle multitasking, and managing large- extremely complex, high-level scale data transactions. calculations. Key Use: Scientific research, weather Key Use: Bulk data processing, such forecasting, simulations, and large- as transaction processing, censuses, scale data analysis. and business operations. Processing: Optimized for processing Processing: Designed to handle a a small number of highly complex large number of smaller, simple tasks tasks very quickly (e.g., solving simultaneously for multiple users. equations or modelling climate systems). Characteristics of mainframe computers and supercomputers Longevity Longevity:  Mainframes have long lifespans, operating continuously for decades with minimal downtime.  They provide strong security through encryption, making them crucial for governments, banks, and telecoms.  Disposing of old mainframes and securing their data is costly, prompting many businesses to modernize rather than replace them. Threats to Mainframes:  Skill Shortages: Maintenance and programming rely on COBOL, an aging language with declining availability in educational curriculums.  Technological Competition: Cloud computing offers flexibility and cost-efficiency, reducing the need for on-premises mainframe hardware. A hybrid solution, combining mainframes and Cloud, could leverage the strengths of both. Comparison to Supercomputers:  Mainframes excel in processing high volumes of transactions and calculations quickly and reliably, ensuring 24/7 operations.  Supercomputers, with a typical lifespan of five years, are frequently replaced by faster models in research and meteorology fields. RAS RAS stands for Reliability, Availability, and Serviceability and is a key feature of mainframe computers, ensuring consistent performance and minimal downtime. Reliability: ◦ The ability of the system to operate without failure. ◦ Mainframes are highly reliable due to self-checking processors that detect and recover from errors without disrupting operations. ◦ Their thoroughly tested software ensures quick updates to address any issues. Availability: ◦ Mainframes are operational for extended periods, with Mean Time Between Failures (MTBF) often measured in months or years. ◦ Even in the event of a failure, recovery is rapid, aided by spare CPUs that automatically replace faulty ones without halting operations. Serviceability: ◦ The ease with which issues can be identified, diagnosed, and resolved, often while the system remains operational. Hardware and software in mainframes can be repaired or updated without significant disruptions. Note: RAS is a defining feature of mainframes and is not commonly associated with supercomputers. Security Mainframe Security: Purpose: Designed to handle large volumes of sensitive data securely, especially in sectors like banking and employee management. Key Features: ◦ User Identification and Authentication: Often includes multi-factor authentication (e.g., password, biometric ID, token, or time-restricted PIN). ◦ Access Levels: Users can only access data based on their clearance level. ◦ Data Encryption: Protects transmitted and stored data. ◦ Secure Operating Systems: Built to prevent breaches. ◦ Continuous Monitoring: Detects and blocks unauthorized access attempts. Supercomputer Security: ◦ It uses End-to-End Encryption which ensures only the sender and recipient can decrypt and understand the data and it is used for storing sensitive data (e.g., DNA profiles). Performance metrics Mainframe Metrics: Measured in: Millions of Instructions Per Second (MIPS). Challenges with MIPS: ◦ Not all instructions are equal in complexity, affecting the time required to process them. ◦ Benchmark tests, comparing CPUs on the same task, provide a better performance measure. Cost Efficiency: MIPS are often linked to cost, calculated as cost per million instructions per second. For example, if a mainframe costs $500,000 and provides 1,000 MIPS, then the cost per MIPS is $500. This metric helps businesses compare the value of different mainframe systems or evaluate the return on investment when upgrading to a newer system. Supercomputer Metrics: Measured in: Floating Point Operations Per Second (FLOPS). Current Speeds: Measured in petaflops (1 petaflop = 1 quadrillion FLOPS), (1,000,000,000,000,000 FLOP). ◦ Fastest supercomputer operates at 148 petaflops, while the tenth fastest achieves 18 petaflops. Future Developments: Exaflops (1 exaflop = 1,000 petaflops) are expected within this decade. Comparison: FLOPS better reflect the performance of supercomputers, whereas MIPS suits mainframe tasks. Volume of input, output and throughput Mainframe Computers: ◦ Have peripheral processors dedicated to input/output operations, freeing the CPU to focus on data processing. ◦ Handle terabytes or more of input data, access large record sets, and produce significant output volumes. ◦ Capable of billions of transactions daily, demonstrating high throughput (the ability to manage large volumes of simultaneous input, processing, and output). Supercomputers: ◦ Throughput is a defining characteristic of mainframes, whereas supercomputers are optimized for raw computational speed, prioritizing processing power and speed over throughput. Tip: Peripheral processors are specialized hardware components in mainframe computers that manage input and output (I/O) operations separately from the central processing unit (CPU). Their primary function is to handle the movement of data between the system and external devices, such as storage, printers, and communication networks, without burdening the CPU Fault tolerance Mainframe Fault Tolerance: ◦ Fault tolerance means that computers can continue to operate even if one or more of its components have failed ◦ The fault tolerance in mainframe computers is high. ◦ Mainframes can continue operating even if one or more components fail. ◦ Hardware Fault Tolerance: If a processor fails, the system switches to another processor without interrupting data processing. ◦ Software Fault Tolerance: Two versions of software are used; if one fails, the other takes over automatically. Supercomputer Fault Tolerance: ◦ Supercomputers have significantly more components (up to a thousand times more processors), making failures more likely. ◦ The fault tolerance of supercomputers is generally lower compared to mainframes. ◦ Similar fault tolerance strategies as mainframes are used, but with the huge number of components, the system may experience interruptions, though recovery is typically fast. Key Difference: Mainframes are more fault-tolerant due to fewer components, while supercomputers are more prone to failures but recover quickly. Operating system Mainframes: ◦ Often run multiple operating systems (e.g., z/OS, z/VM®, and Linux®) simultaneously. ◦ Use parallel processing, where a task is divided into sub-tasks and assigned to different processor cores. Once processed, the results are recombined for output. ◦ This approach makes mainframes more efficient than PCs, even those with multiple cores. Supercomputers: ◦ Typically run a single operating system, usually Linux, which is popular due to its open-source nature. ◦ Employ massively parallel processing where many processor cores work independently, each with its own OS. ◦ Supercomputers typically have hundreds of thousands of cores, each performing individual calculations simultaneously. Key Difference: Mainframes run multiple OSs for parallel processing, while supercomputers focus on parallel processing with many independent processor cores, all typically running Linux. Number of processors Early Mainframes: ◦ Initially had just one processor (the CPU), but over time, multiple processors were added. The terms "CPU" and "processor" became less distinct as systems evolved. ◦ Mainframes now typically have hundreds of processor cores. Supercomputers: ◦ Feature hundreds of thousands of processor cores. ◦ Modern supercomputers also use multiple GPUs (graphics processing units), unlike mainframes. Key Difference: Supercomputers have far more processor cores and also incorporate GPUs, making them vastly more powerful than mainframes in terms of processing capacity. Tip: A GPU (Graphics Processing Unit) is a specialized processor designed to accelerate the rendering of images, videos, and animations. Originally developed for handling graphics-related tasks, GPUs have become increasingly used for general-purpose computing due to their ability to handle massive parallel tasks efficiently. Heat maintenance Both mainframes and supercomputers face significant overheating issues due to the large number of processors. Mainframes: ◦ In the early days, liquid cooling systems were used to manage heat, but as technology advanced, air cooling became sufficient. ◦ However, with the introduction of more powerful hardware, mainframes started producing more heat, causing air cooling to become complex and expensive. ◦ As a result, liquid cooling systems have become more cost-effective and are now recommended again for larger mainframe machines. Supercomputers: ◦ Supercomputers have always faced overheating challenges due to their massive power consumption (up to 4 megawatts, enough for thousands of homes) and the close arrangement of processors. ◦ This generates a lot of heat, requiring direct liquid cooling to maintain optimal performance and prevent damage to components. In summary, both mainframes and supercomputers rely on liquid cooling to handle excessive heat generated by their powerful processors. Liquid- Cooling  Mainframe computer uses - Census. A census typically refers to a population census, which is an official survey conducted to determine the number of people and households in a country. A census is typically conducted every ten years. The processing of census data has been linked with computers since 1951. Census collects details about people’s ages, types of employment, and other demographic information. It involves processing vast amounts of information, making it a data-intensive task. Technological innovations have led to the development of new generations of mainframe. computers, improving data processing and manipulation capabilities for census agencies. Mainframes were crucial in processing the growing amounts of data generated by increasing populations. By 2000, improvements in PC processing power and storage offered a cost-effective alternative, leading many countries to move away from expensive mainframe systems. Industry statistics Industry statistics refer to data collected about trends in various industries, including raw material processing, manufacturing, and services. It Includes details such as the number and names of businesses, the number of employees, and wages paid. Some businesses, particularly in specific industrial sectors, use mainframes to process large amounts of data. Industrial statistics helps businesses identify major competitors, their market share, and sales trends. Assists in recognizing products that could compete profitably in the market. Companies that do not process their own data can purchase reports from organizations specializing in data collection, and these organizations may use mainframes for processing. Consumer statistics Consumer Statistics helps businesses assess the demand for their products by understanding how many people need or want them. It Includes information on household incomes and employment status of potential consumers, aiding in setting appropriate prices. Indicate where consumers live for targeting local sales and their likelihood of using the internet for shopping. Provide details on the availability of similar products and their pricing, helping businesses understand competition. The collection and analysis of consumer statistics generate vast amounts of data. Organizations producing consumer statistics are likely to rely on mainframes to process this extensive data efficiently. Definition and Process of Transaction Processing: A transaction consists of multiple computer operations that must combine to make a single, error-free transaction. If an error occurs during any operation, all traces of the transaction are removed, and the system acts as though it never happened. If there are no errors, the transaction updates the relevant database before moving on to the next transaction. Transactions are processed in milliseconds to appear immediate to users. Example of Transaction Processing - Bank Account Transfers: For example, transferring $100 from a customer’s account to a supermarket's account involves: 1.Subtracting $100 from the customer’s account. 2.Adding $100 to the supermarket’s account. If either operation fails, the transaction is cancelled to maintain accurate records. Role of Mainframe Computers in Transaction Processing: High Performance: ◦ Mainframes are effective due to their ability to perform hundreds of Millions of Instructions Per Second (MIPS). Continuous Availability: ◦ The system is designed to operate without downtime, even when hardware or software problems occur. Data Integrity: ◦ Mainframes ensure data integrity, even during hardware or software failures. Serviceability and Maintenance: ◦ Hardware and software can be added, replaced, or updated without shutting down the system. Core Redundancy: ◦ Mainframes can transfer processing between cores, enhancing reliability and efficiency. Supercomputer uses 1.National Defense: Initial use included designing nuclear weapons and data encryption. 2.Scientific Research: Crucial for advanced fields such as quantum mechanics (the behaviour of particles at the smallest scales). 3.Weather Forecasting and Climate Research: Essential for analyzing large datasets and making accurate predictions. 4.Drug Research: Compares new drug development results with prior research data. Monitors and adjusts ingredient amounts with precision. Uses complex computer models to simulate structural changes in drugs and their effects on the body. 5.Genetic Analysis: Identifies genes associated with susceptibility to diseases. Handles the massive calculations required, reducing processing time from months to minutes. Core Strength of Supercomputers: They provide maximum computational power, making them crucial for tasks requiring high precision and rapid processing in fields like drug manufacturing and genetic research. Quantum mechanics Quantum Mechanics studies the behavior of matter and light at atomic and subatomic scales, focusing on particles like electrons, protons, and neutrons. These particles do not follow the same physical laws as larger bodies. While understanding it is not essential, many calculations in quantum mechanics require great precision and the use of supercomputers. Used by physicists in Germany for complex quantum calculations, such as determining the mass difference between neutrons and protons, and predicting dark matter composition. It had a maximum performance of 5 petaflops with 459,000 cores. Weather forecasting Weather Forecasting relies on complex computer models to predict weather patterns. Data from weather stations around the world, including readings like atmospheric pressure, humidity, rainfall, temperature, wind speed, and direction, are input into the models. The model compares current weather with historical records to identify patterns and predict future conditions. In addition to weather stations, data from radar, satellites, space soundings, and observations from ships and aircraft are used. The supercomputer generates a 3-D model of Earth's atmosphere based on the collected data. Due to the complexity and volume of calculations, supercomputers are required to perform the necessary computations. Climate research Climate is measured over long periods, with data collected over several decades to show trends in variables like nitrogen dioxide, sulfur dioxide, ozone levels, and air quality. Rivers are monitored for variables such as temperature, pH, dissolved oxygen, turbidity (cloudiness), and water level. Climate is studied as part of Earth's complex system, which includes factors like heat from the Sun, ocean currents, vegetation, ice (land and sea), weather, volcanoes, and human activity. The interactions between Earth's components can be described mathematically, but due to the complexity and many variables, supercomputers are necessary for calculations. Supercomputers are used to run models that simulate Earth’s climate system. As climate change becomes a serious issue, many organizations are developing supercomputer models. Advantages of mainframe computers Reliability: Mainframes are highly reliable, with rare system downtimes, making them ideal for organizations like banks. Unlike PCs or laptops, which often require reboots, mainframes can run continuously without interruptions. Upgrades Without Downtime: Mainframes can undergo hardware and software upgrades while still operating, ensuring minimal disruption. Power and Performance: Mainframes are increasingly faster and more powerful, outperforming PCs, laptops, and other devices. Data Handling: Mainframes can process and store vast amounts of data, making them essential for organizations with large data needs. Transferring data from a mainframe to another system would be extremely challenging. Compatibility with Multiple Operating Systems: Mainframes can run different operating systems and handle various database formats, which other platforms may struggle with. Security: Mainframes offer stronger security compared to other systems, with complex encryption and authorization procedures in place. The disadvantages of mainframe computers include: High Cost: Mainframes are very expensive to purchase, making them accessible mainly to large organizations like multinational banks. Additionally, the cost of personnel to run and maintain them is high. Space Requirements: Mainframes require large rooms for housing, unlike smaller systems that need less space. Cooling Costs: As mainframes become more advanced, the cooling systems necessary to maintain their operation become more costly to install and operate. Migration to Cloud Services: Many organizations are moving to Cloud-based services to avoid the expense of buying and maintaining their own mainframe systems, as well as the need for specialized expertise. Software Costs: The software required to run mainframe systems is more expensive than using Cloud-based alternatives. Advantages and disadvantages of supercomputers Advantages of Supercomputers: Fastest Data Processing: Supercomputers are the fastest data processing computers, capable of handling massive calculations at incredible speeds. Massively Parallel Processing: They use massively parallel processing, which makes them far more powerful than mainframes and PCs, allowing for complex computations and simulations. High Performance: Supercomputers have a much greater number of processor cores compared to PCs, providing significantly more processing power. Disadvantages of Supercomputers: High Cost: Supercomputers are very expensive to buy and install. For example, the Summit supercomputer cost $200 million, far exceeding the cost of mainframes. Single Operating System: Unlike mainframes, which can run multiple operating systems simultaneously, most supercomputers are limited to one operating system. Lower Fault Tolerance: Supercomputers are less fault-tolerant than mainframes. If one component fails, recovery can be slower, leading to more downtime than mainframes (though still less than some other systems). System software: refers to the programs that run and control a computer’s hardware and application software. Compiler: Translation from High-Level to Machine Code: A compiler translates a program written in a high-level language (source code) into machine code (object code) that a computer’s processor can execute. Production of an Executable File: The compiler creates an executable file (object code), which can run independently without the need for the compiler to be present. Whole Program Translation: The entire program is translated as one unit, though the compiler may need to make multiple passes through the program to complete the translation. Multiple Passes: ◦ First Pass: It might scan the program to collect all variable and function declarations, ensuring that the program structure is understood. ◦ Second Pass: It resolves references between different parts of the program, like ensuring a function used in line 10 is declared in line 5. ◦ Final Pass: It converts the program into machine code. Error Detection: A compiler generates a list of error messages after translating the program. These errors must be fixed by editing the source code. Execution One Instruction at a Time: The machine code (object code) produced by the compiler is executed by the processor one instruction at a time. Compiler: Output Processor Translation Execution A compiler generates a list of error messages after translating the program. These errors must be fixed by editing the source code. Compiler: Advantages Disadvantages Faster Execution After Compilation: Longer Development Time: ◦ Once compiled, the program runs quickly because ◦ Compilation can be a lengthy process, and errors it has already been translated into machine code. are only revealed after the entire program has been processed. Standalone Executable: ◦ A compiled program can be executed without Platform Dependence: requiring the source code or the compiler, ◦ A compiled program will only run on systems with reducing risks of copyright infringement. the same operating system as the one it was compiled on, limiting portability. Error Reporting in Bulk: ◦ The compiler outputs all error messages at the High Memory Usage: end of the process, providing a complete overview ◦ The entire program must be loaded into memory of issues to fix. before translation, requiring more system resources. More Secure Code: ◦ Machine code produced by the compiler is harder Debugging Challenges: to understand or modify, offering better protection ◦ All errors are reported together after compilation, for intellectual property. making it harder to pinpoint and fix specific issues quickly. Interpreter: Line-by-Line Translation: An interpreter translates one statement or line of code at a time into an intermediate form and executes it immediately. Stops on the First Error: The interpreter stops translating and executing as soon as it encounters an error, allowing the programmer to identify and fix errors at the exact location they occur. Translation During Execution: Translation and execution happen simultaneously, meaning the interpreter must remain in memory while the program runs. Memory Efficiency: Only a few lines of the program need to be in memory at a time, saving memory space. Helpful for Program Development: Interpreters allow programmers to test and debug programs incrementally by executing each statement as it is entered. They also generate helpful error reports. No Independent Executable File: Unlike a compiler, an interpreter does not produce a separate executable file. Instead, it translates and executes the program directly. Bytecode Processing with Virtual Machines: Some programs, like Python and Java, use a combination of a compiler and an interpreter. The source code is compiled into bytecode, which is then executed by a virtual machine (an interpreter), instead of the computer's processor. 2 Interpreters Advantages Disadvantages Immediate Error Detection: Slower Execution: ◦ Errors are detected and reported as they occur during program execution, allowing programmers to correct them ◦ Programs are slower because each immediately. statement is translated and executed line by line every time the program Faster Debugging: runs. ◦ Debugging is easier because error messages are output line by line, making errors simpler to locate and fix. Requires Source Code Availability: System Independence: ◦ The source code must be present for ◦ Source code can run on any system with the appropriate execution, which poses risks to interpreter, increasing portability. software copyright and intellectual property rights. Memory Efficiency: ◦ Only a small portion of the program needs to be loaded Translation Dependency: into memory at a time, making it ideal for testing small code segments incrementally. ◦ The interpreter must be present on the system for the program to run, making Quick Testing During Development: it less self-sufficient compared to ◦ Programmers can test parts of the code without having to compiled programs. compile the entire program. The main program is divided into modules or subprograms, which are compiled separately. This approach saves time and effort for programmers by allowing for easier debugging, testing, and maintenance. Linker: Combines Object Files into a Single Executable: The linker takes object files (modules) created by a compiler and combines them into one complete executable file. Supports Modular Programming: Programs can be written in smaller, modular pieces, often by different programmers. The linker integrates these modules into a unified program, enabling collaborative development. Efficient Use of RAM: Large programs can be compiled in smaller parts (modules) to accommodate limited RAM. The linker combines these parts after compilation, reducing memory requirements during the process. Storage Management: Object files can be stored on backing storage (e.g., hard drives) during compilation and then retrieved and linked later, allowing for efficient handling of large programs. Error Isolation: If a module contains an error, only that specific module needs to be corrected. The linker can then incorporate the updated module into the program. Cost Savings: Modular programming facilitated by a linker reduces RAM usage, potentially saving money on hardware costs. Challenges with Variable Names: Using a linker requires careful handling of variable names to avoid conflicts when combining modules. Requires Detailed Documentation: Since programs are developed in modules, detailed documentation is necessary to ensure the modules work correctly when linked together. Writing and understanding this documentation can be time-consuming. Linker: Compiler Compiler Compiler Compiler Device driver A device driver is a small program that allows the operating system (OS) and application software to communicate with hardware devices. For example, a printer driver serves as an intermediary between the OS, application, and printer, enabling the user to control the device. Drivers are necessary for various hardware like sound cards, monitors, mice, and keyboards. Because hardware and software are often created by different companies using different languages, device drivers act as "translators," ensuring communication between the two. Without the correct driver, the OS cannot interact with the hardware, the hardware becomes "non- functional" or unusable without the appropriate driver. Modern OSes include basic drivers for common hardware, but advanced features or new devices may require specific drivers. Additionally, drivers are typically OS-specific and are not interchangeable between different operating systems. Operating system: An operating system (OS) is system software that manages hardware, software resources, and user interaction. It is loaded during the computer's boot-up process, initiated by the BIOS stored in ROM. The OS acts as an interface between users, application programs, hardware, and device drivers, and provides essential utilities for managing the computer. Functions of the OS:  Memory Management: Allocates RAM to each program, preventing data overlap or corruption that could lead to crashes.  Input/Output Management: Uses device drivers to handle data from input devices and send instructions to output devices like printers.  File Management: Tracks file locations, manages storage spaces, and records file details such as start and end points.  Multitasking: Allocates time to multiple running programs or tasks, ensuring fair and efficient operation.  Error Handling: Displays error messages to users and waits for corrective actions, such as when invalid file names are entered.  Security: Encrypts and verifies user passwords, manages file access permissions, and restricts sensitive data to authorized users.  Shutting Down: Closes all running programs safely and powers off the computer systematically. Host Computer: The computer where the source code is written and the compilation process happens. It has the tools (e.g., compilers) installed to translate the source code into machine code. Example: A developer's PC. Target Computer: The computer where the compiled program is intended to run. It may have a different operating system, processor architecture, or hardware configuration than the host computer. Target Example: A microcontroller, game console, or a different type of PC. Machine - Native x86 compiler Native Compiler: A compiler that generates machine code for the same system as the host computer. The compiled program runs on the same operating system and processor architecture as the host. Example: A compiler running on a Windows computer to generate programs for Windows. Cross-Compiler: A compiler that generates machine code for a different system than the host computer. It is used when the target computer has a different processor architecture or operating system from the host. Example: A cross-compiler running on a Windows computer that produces machine code for a Raspberry Pi (Linux and ARM architecture). Uses of system software How a high-level language is translated to run on different computer systems using interpreters When transferring a program to a computer with a different operating system or processor, programmers often use interpreted programs written in high- level languages. Interpreted programs remain in source code form and can run on different systems because they are translated by an interpreter on each target computer. While this approach allows compatibility across various systems, it is slower than using a compiler and requires a suitable interpreter on the destination computer. Supplying the interpreter with the program adds complexity compared to compiled programs. How a high-level language is translated to run on different computer systems using cross compilers A cross-compiler is a software tool that translates source code written on one computer (the host computer) into machine code that can run on a different computer (the target computer) with a distinct architecture or operating system. Characteristics: Purpose: Enables developers to create software for systems that differ from the one they are working on, such as embedded systems, game consoles, or other specialized devices. Output: Produces machine code specifically for the target system's processor and architecture. Use Case: Common in embedded systems development, where the target device may lack the resources to run a native compiler. Example: A programmer writes a program on a Windows computer for a microcontroller running on an ARM architecture. A cross-compiler converts the source code into machine code that the ARM-based microcontroller can execute. Challenges: The compiled program can't run on the host system. Cross-compilers may introduce more errors compared to native compilers. Debugging and optimization for the target system can be more complex. The Need for Utility Software and Its Uses: Utility software is a type of system software that is needed to help maintain a computer system. While operating systems typically provide a basic set of utilities to handle tasks such as file management and storage device maintenance, users may need additional utilities for more specialized functions that the OS doesn't offer. These utilities are crucial for the proper functioning of a computer, as they help manage files and ensure the system runs efficiently. Uses of utility software include: ◦ File Management: Utility software helps with handling files and associated storage devices, ensuring smooth file operations. ◦ Memory Management: Utilities are required to manage and allocate computer memory, improving system performance. ◦ Customization: Utility software enables users to customize the appearance of their desktop to suit their preferences. In essence, without utility software, a computer system would not operate effectively or be as customizable and efficient. The Structure A hard-disk of ofHard drive (HDD) consists Disk Storage: several platters (individual disks), each with its own read-write head for both the top and bottom surfaces. These read-write heads float on a thin air film and read or write data to the platter surfaces without physically touching them. Platters and Tracks: The platters are stacked on top of each other and spin together at the same speed. Each platter surface is divided into several tracks, and each track is further divided into sectors. The tracks on each platter are aligned so that corresponding tracks on different platters form a cylinder. Data Writing Process: Data is written starting from the outermost track of the first platter, then moves inward across subsequent tracks and platters. As data fills each cylinder, the heads move toward the center to write data on the next available track. Sectors and Blocks: Each sector typically holds 512 bytes of data. Operating systems manage data in blocks, which can consist of one or more sectors (e.g., one, two, four, or eight sectors). This structure allows HDDs to efficiently store and retrieve large amounts of data. Formatting: Formatting a hard disk is the process of preparing it for use by a computer. It is necessary because a new disk is initially unusable. Formatting can also be done to remove data or when replacing a hard disk in a computer. There are two types of formatting: Low-Level Formatting: This sets up the structure of the disk by dividing it into cylinders, tracks, and sectors. It is typically done by the manufacturer. Repeated low-level formatting can damage the disk and make data recovery difficult. High-Level Formatting: This erases the pointers (stored in a File Allocation Table) that the operating system uses to locate data, but the data itself remains recoverable. High- level formatting is commonly used to erase a disk and reinstall the operating system, and can also remove viruses. Formatting can also involve partitioning, where a disk is divided into separate sections for different purposes. This allows for separating the operating system from user data, encrypting sensitive files, and protecting data during OS reinstallation. Partitions are managed using a partition table that stores the locations and sizes of partitions. System administrators can use a partition editor to create or modify partitions. Disk Defragmentation: Disk defragmentation is the process of organizing fragmented data on a disk to improve data retrieval speed and increase storage capacity. When a file is saved, it may be split into multiple blocks that are scattered across the disk due to insufficient empty sectors. This fragmentation causes slower data access as the read-write heads need to move across the disk to retrieve all parts of the file. Defragmentation software works by rearranging these fragmented blocks, making the file contiguous and easier to access, which speeds up data retrieval. It also frees up additional storage space by consolidating smaller files and reorganizing others. In cases where it is impossible to fully reunite a file's blocks, the software will move as many as possible into sequential order, optimizing disk performance. Data compression reduces the storage space occupied by files on a disk and speeds Data Compression: up the transmission of large files over networks or as email attachments. It can be lossless or lossy. Lossless compression: is a method of data compression where the file can be perfectly restored to its original state after decompression, without losing any data. It works by identifying repeated sequences of bits and replacing them with a special marker that indicates what is being repeated and how many times. This type of compression is commonly used for files like spreadsheets, databases, and word-processed documents, where even a single bit of data loss could significantly alter the content's meaning. For example, the GIF and PNG format supports lossless compression. Lossy compression: is a method of data compression where unnecessary data bits are permanently removed. It is typically used for images and audio files, where the loss of some data has minimal impact on quality. For example, the JPEG format supports lossy image compression. Advantages of data compression include faster file transmission and reduced storage space, which saves costs and allows for the streaming of high-definition videos. However, it has some downsides, such as increased memory usage during compression, slower file opening times, and a reduction in quality with lossy compression. Backup A backup is an exact duplicate of files or data created to restore the original files in case they are corrupted, deleted, or lost. It ensures data security by storing copies of files from a computer or server’s storage. Features of Backup ◦ Customizable Scheduling: Users can select the time, type, and frequency of backups. ◦ Storage Location: Backups can be stored on external drives, tapes, or in the Cloud, often in a different physical location for added security against disasters. ◦ Data Verification: Backups can be verified using checksums to ensure data integrity. ◦ Encryption: Backups can be encrypted for enhanced data security. Types of Backup ◦ Full Backup: Copies all data, providing a complete duplicate of files. ◦ Incremental Backup: Backs up only data that has changed or been added since the last backup, saving time and storage but complicating restoration. ◦ Differential Backup: Backs up all data that has changed since the last Advantages and Disadvantages of Different Types of Backup 1. Full Backup  Advantages:  Provides a complete duplicate of all data.  Simplifies restoration since all files are contained in one backup.  Disadvantages:  Takes a long time to perform.  Requires a large amount of storage space. 2. Incremental Backup  Advantages:  Saves time and storage space by only backing up data added or changed since the last backup.  Efficient for frequent backups.  Disadvantages:  Restoration can be complex, as it may require several backups to rebuild the system. 3. Differential Backup  Advantages:  Backs up all changes since the last full backup, simplifying restoration.  Only two backups (last full and most recent differential) are needed to restore the system.  Disadvantages:  Requires more time and storage than incremental backups, as it repeatedly backs up changes. File Copying: File copying is the process of creating a duplicate of an existing file, ensuring the copy has the same content as the original. This is often done to work on a temporary version while preserving the original. File copying can be performed through: ◦ Command Line Interface (CLI): Using commands like "copy" to specify the original file and destination folder. ◦ Graphical User Interface (GUI): Using mouse actions, such as right-clicking to copy and paste between folder windows. This results in two identical files stored in separate locations. Deleting: File deleting is the process of removing files, often to free up disk space. The delete utility works by erasing the pointers that locate the file on the disk, marking the sectors as available for new data. Until new data overwrites the file, it can be recovered using data recovery software, which restores the file's pointers. However, if data has been overwritten, recovery becomes highly challenging. In many systems, pressing the delete button moves the file to a temporary folder, such as the recycle bin or trash, where it can be retrieved if needed. Full deletion occurs when this folder is emptied. Anti-virus: A virus is a type of malicious software (malware) that can infect a computer or system by attaching itself to a legitimate program or file. Once activated, it can spread to other files, programs, or systems, often causing damage such as corrupting or deleting data, stealing information, or disrupting system operations. Viruses typically require a user to execute or open an infected file or program to activate, and they often spread through infected attachments, downloads, or shared files. Unlike other types of malware, a virus can replicate itself and spread to other computers. Anti-virus software is a program or set of programs designed to detect and remove viruses and other types of malware, such as worms, Trojan horses, and adware. Its features include: Detection and removal: It identifies and either removes or quarantines viruses and malware. Prevention: It helps prevent attacks from malware by continuously monitoring the computer. Regular updates: To stay effective, it must be kept up to date as new viruses and malware are frequently created. Scanning options: It allows users to scan specific files, folders, or the entire system for threats. Automatic scanning: Users can schedule scans to run automatically at set times. The different methods of detecting a virus include: Signature-based Detection: ◦ Compares files to a database of known virus signatures (unique byte sequences). ◦ Effective for detecting known viruses but unable to identify new, unknown threats. Heuristic-based Detection (Static Heuristic): ◦ Decompiles and analyzes a program's source code, comparing it to known viruses. ◦ Flags files as potential threats if they match a certain percentage of virus code. ◦ Can result in false positives when non-malicious files accidentally match virus sequences. Behavioral-based Detection (Dynamic Heuristic): ◦ Monitors for abnormal behaviors, such as sending large numbers of emails or altering critical files. ◦ May also produce false positives. ◦ Can be used in a sandbox environment, where suspected malware is executed in a virtual space to prevent harm while being analyzed. Other types of utility software A file management system is software that organizes and manages data files on a computer. It allows users to perform tasks like copying, deleting, and naming files. Files can be named using most characters, but some are restricted. The system enables users to create directories to store and organize related files, and it helps move files between directories. The system displays files in a user interface and allows browsing, sorting, and searching by criteria like date, size, and type. It also manages file metadata, which includes details such as file name, size, location, and modification dates. Disk Management systems are software utilities that help users manage their hard disk drives. These utilities can format, partition, compress, defragment, and back up disks. Additional features allow users to assign names to disks, initialize new drives, extend or shrink partitions, and change drive letters. For example, users can rename partitions (e.g., "Photos" or "Personal") and extend storage space by reallocating unallocated space, often by deleting or shrinking other partitions. While it's possible to change drive letters, it’s typically advised not to modify system partitions like C: and D:. Custom-written software Custom-written software is specifically developed for a particular task, organization, or individual. Large companies may hire programmers to create such software for unique needs or problems. Once developed, the company owns the software and may sell it to others. Uses by individuals and organisations: Organizations use databases for tasks like employee records, stock control, and customer accounts, requiring specialist programming. Websites tailored to specific needs are essential for banks, online stores, and sports clubs. While individuals typically rely on cost-effective off-the-shelf software, small businesses with unique or complex requirements may need custom-written software, such as integrated solutions combining websites, databases, and spreadsheets. Off-the-shelf software Off-the-shelf software is pre-existing and ready to use immediately. While it can be adapted to an organization's needs, it may require significant storage space. Unlike custom-written software, the purchasing organization does not own it and cannot resell it, even after modifications. It is owned by the company that created it. Uses by individuals and organisations: Smaller organizations often use pre-made business software from large companies, such as invoicing, accounting, payroll, or web design tools, which offer commonly needed features like text editing, accounting, and mail merge. Individual users typically utilize basic word processing and spreadsheet functions. However, these software packages may include unnecessary features. Advantages of Off-the-Shelf Software: Cost-effective: Cheaper to purchase as it is mass-produced and shared among many customers. Immediate availability: Ready to use without the need for development time. Extensive support: Includes forums, websites, and helplines with experienced operators for assistance. Thoroughly tested: Rigorously tested with existing bugs identified and fixed. Wide usage: Proven reliability due to extensive use by other customers. Disadvantages of Off-the-Shelf Software: Limited customization: May not fully meet specific customer requirements and can be difficult to adapt. Unnecessary features: Might include features that are irrelevant to the customer’s needs. Compatibility issues: May not work seamlessly with the customer's hardware or operating system, with settings that cannot be altered. Advantages of Custom-Written Software: Tailored to needs: Specifically designed to meet all customer requirements without unnecessary features. Customizable: Programmers can make alterations to match exact customer needs. Compatibility: Designed to work seamlessly with the customer’s existing hardware and operating system. Copyright ownership: The customer owns the copyright, allowing potential resale and additional income. Disadvantages of Custom-Written Software: High cost: More expensive due to the need for development from scratch. Long development time: Requires significant time for development and consultation with programmers. Limited support: Support is dependent on the availability of the original programmer or a User interfaces A user interface (UI) enables communication between the user and the computer system via input devices and the operating system. A good UI is user-friendly, intuitive, and allows seamless interaction. Users should easily predict outcomes of their actions, like pressing a button. The four main types of interfaces are: Command-line interface Graphical user interface Dialogue interface Gesture-based interface The Command Line Interface (CLI) is a way for users to interact with a computer by typing commands in the form of text. It displays a prompt on the screen where users input commands, and the computer executes them. The CLI is less common today but is still used by advanced users such as software developers and system administrators. Uses of Command Line Interface (CLI): 1. Preferred by software developers, system administrators, and advanced users for precise control over systems. 2. Allows performing tasks such as navigating files, running software, and configuring systems. 3. Often used within graphical user interfaces (GUIs) for specialized tasks. 4. Useful for automating repetitive processes with scripts. GUI: A Graphical User Interface (GUI) was developed to provide a more efficient and user-friendly way of interacting with computers compared to the Command Line Interface (CLI). The GUI uses windows, icons, menus, and pointers (collectively known as a 'WIMP' interface) to execute commands. It allows users to interact with files, programs, and settings by visually selecting options rather than typing commands. Uses of GUI: Managing files: Users can open, delete, and move files by interacting with icons and menus. Running applications: Users can double-click on an icon to open a program or file. Navigation: Users can navigate through options and settings using a mouse or touchscreen, depending on the device. A Dialogue Interface A dialogue interface lets users interact with a computer or device using voice commands. Speech-recognition software converts spoken words into actions, enabling tasks like making phone calls or switching radio channels in cars. Laptops and PCs also support voice control for running software and opening files. The system learns the user’s speech patterns through repeated sentences but may struggle with background noise or a limited vocabulary. Uses of Dialogue User Interface: In Vehicles: Allows drivers to control their phone or radio without touching them, making the driving experience safer and more convenient. For example, drivers can say “phone Graham” to make a call or change radio channels by voice. On Laptops and PCs: Users can load and run software or files by speaking commands into a microphone, offering a hands-free option for interacting with computers. Smart Devices: Used in various devices with voice control, allowing users to interact with them through simple voice commands, such as controlling smart home appliances or navigating menus. Customer Service Systems: Integrated into automated systems where users can interact with virtual assistants or automated phone systems, enhancing the customer experience. Personal Assistants: Popular in virtual assistants (e.g., Siri, Google Assistant) for setting reminders, sending messages, or fetching information via voice. A Gesture User Interface (GUI) allows a user to interact with a computer or device using physical gestures. These gestures, made with the face, hand, or other body parts, are interpreted by the system and converted into commands. A camera and infrared sensor detect movements, and the computer uses specialized software to match the gesture with stored ones in a database. Each matched gesture triggers a specific command. Uses of Gesture User Interface: Smart Homes: In smart homes, users can control devices like lights, thermostats, and appliances through gestures. For example, a wave of the hand can turn the lights on or off. Gaming: Gesture-based interfaces are commonly used in video games, where players control characters or interact with the game environment using their body movements. Healthcare: Gesture interfaces can be used in medical technology, allowing doctors or patients to control devices or equipment without physical contact, which is important in sterile environments. Virtual Reality (VR) and Augmented Reality (AR): In VR/AR, gestures allow users to interact with digital objects or environments, creating more immersive experiences. Advantages and Disadvantages of Different Types of User Interface: Graphical User Interface (GUI) Disadvantages: Advantages: Not suitable for all disabilities: User-friendly: GUIs are typically Users who can't use a mouse or intuitive and easier to use, especially keyboard may find GUIs unsuitable. for non-experts. Requires more resources: GUIs Accuracy: More accurate than require higher processing power and gesture or dialogue interfaces, as the storage space compared to CLIs. mouse pointer can precisely select Learning curve with updates: GUI items like icons. designs tend to change over time, Widely used: GUIs are common and requiring users to relearn how to use compatible with most devices and new versions. software. Easier to edit: Errors can be easily corrected using a mouse, unlike in a command-line interface (CLI). Command-Line Interface (CLI) Gesture-Based Interface Advantages: Advantages: Precise commands: CLIs allow for Hands-free interaction: Gesture interfaces can precise, text-based input. be useful for users in environments where Less resource-intensive: CLIs touching devices (like a mouse or keyboard) is consume less processing power and impractical, such as the food service industry. Intuitive for some users: Gestures, such as storage compared to GUIs and other waving a hand or nodding, can be natural ways advanced interfaces. Stable: Once users learn a CLI, they do to interact with a device. More flexible: Suitable for various scenarios, not need to relearn it with updates. like smart homes, VR, and AR, where users can control devices or systems with their body Disadvantages: movements. Difficult for beginners: CLIs require users to have specific knowledge of Disadvantages: commands and syntax. Accuracy issues: Gestures may not always be Error-prone: Misspellings or incorrect recognized accurately, leading to incorrect commands can cause system failures. actions. Errors are harder to correct than in GUIs. Cultural differences: Some gestures may have Not suitable for all users: Not ideal different meanings in various cultures, leading to for users with disabilities or those who misunderstandings. prefer visual or more intuitive interfaces. Not suitable for all users: Users with limited mobility or those unable to make specific gestures may find this interface difficult to use. Hardware requirements: Requires advanced sensors and software to interpret gestures, which Dialogue Interface Conclusion: Advantages: The choice of interface depends Voice-based control: Dialogue interfaces are on the user's needs, environment, useful for users with disabilities that prevent them and physical abilities. GUIs are from using a mouse or keyboard, as they can generally preferred for ease of control the device with their voice. use, while CLIs are favoured by Hands-free interaction: Ideal in situations where experts for their efficiency and users need to maintain physical contact with lower resource requirements. another object, like driving a car, as it allows control without distraction. Gesture and dialogue interfaces Simple commands: Once learned, dialogue provide unique advantages in systems can quickly recognize and execute specific contexts, such as hands- commands. free control, but may face accuracy and usability challenges. Disadvantages: Background noise issues: Dialogue systems may misinterpret commands if there is background noise, leading to errors. Limited vocabulary: Speech recognition software may struggle with a limited vocabulary or understanding accents and dialects. Requires learning: The system needs to learn the user's voice, which can take time and effort. Higher development costs: Dialogue systems