Software Development Fundamentals

Computer System Introduction

• A computer system comprises interconnected units: input unit, memory unit, control unit, ALU (Arithmetic Logic Unit), registers, and output unit.
• These units work together to process input data into output information.
• Mobile devices, often classified as computers, are commonplace and play an increasingly important role in global communication.

A World of Information

• Computers are ubiquitous, found in various settings like work, school, and homes.
• Computers serve as primary tools for local and global communication worldwide.
• ATMs (Automated Teller Machines), onboard navigation systems in vehicles, and leisure activities (like gaming and listening to music) are typical examples of embedded computer applications.

What Is a Computer?

• A computer is an electronic device governed by instructions stored within its memory.
• Computers can process data according to specified rules, producing and storing results for future use.

Data and Information

• Computers process raw data into usable information.
• Data is unprocessed information, including text, numbers, images, audio, and video.
• Information carries meaning useful to humans.

Computer Characteristics

• Computers operate at high speeds using electronic circuits.
• Modern computer components are generally reliable and rarely fail.
• Consistently, identical inputs and processes will produce the same results.
• Computers rapidly transfer data between storage and memory for processing and future storage.
• Computers can communicate with other computers, enabling resource sharing.

Computer Misuse

• Prolonged or improper use of computers can lead to health problems affecting hands, wrists, elbows, eyes, neck, and back.
• Poor workplace design, posture, and inadequate breaks can increase health risks.
• Computer addiction and technology overload are behavioral health concerns.
• Violations of privacy can occur through misuse or disclosure of personal information.

Networks and the Internet

• A computer network connects multiple computers and devices via communications.
• Networks allow shared resources (hardware, software, data, and information).
• The server controls resources, while clients (workstations) request them.
• The Internet is the world's largest computer network, connecting numerous businesses, government agencies, and individuals.

The Internet

• People use the Internet daily for a variety of reasons, including communication, research, shopping, banking, online training, and entertainment (e.g., online games, video watching).
• Downloading music, photos, and video sharing are common online activities.
• Instant messaging (IM) allows real-time interactions, similar to group discussions.
• Web sites, pages are interconnected, and a collection of related pages forms a website.
• Informal websites, such as blogs, consist of dated articles.
• A website that lets people use software, such as sending emails or preparing documents, is called a web Application.

Computer System Components

• A computer has various electronic, electronic, and mechanical components, called hardware.
• Input devices (keyboard, mouse, microphone, scanner, web cam) allow data entry.
• Output devices (printer, monitor, speakers) display information.
• The system unit, a housing for the computer's circuitry, usually includes a motherboard.
• Storage devices (hard drives, optical discs) hold data, instructions, and information permanently.
• Communications devices (modems) allow computer-to-computer interaction via various media.

System Unit

• The system unit acts as a housing for the computer's electronic parts, and is typically attached to a circuit board referred to as a motherboard.
• Key components include the processor (CPU) and memory.
• Processors interpret and execute instructions.
• Memory stores instructions and data.

Storage Devices

• Storage devices hold data, instructions, and information for later use.
• These devices include USB drives, hard drives, and memory cards.
• Storage devices record or retrieve items to and from storage media.

Communications Devices

• Communications devices enable a computer to send and receive information to other computers or mobile devices.
• Modems and other communication devices use different transmission media, including cables, telephone lines, and wireless connections (e.g., cellular, satellite).

Operating System Introduction

• The operating system (OS) facilitates communication between computer hardware and applications, enabling efficient user interaction.
• Basic functions include process management (managing different programs), memory management (allocating memory to running processes), file system management (organizing files on storage), and device management (controlling communication with hardware devices)

Key Components of an Operating System

• Kernel: The operating system's core that manages hardware and provides fundamental services
• Device Drivers: Software to handle communications between the OS and hardware devices
• File System: Manages the storage, organization, and retrieval of data

Shell/User Interface

• The user interface allows users to communicate with the operating system; it can be a command-line interface or a graphical user interface.
• Command-line interfaces (CLIs) help experienced users with automation tasks.
• The Graphical User Interface (GUI) uses graphical elements (icons, buttons) for user-friendly interaction.

Types of Operating Systems

• Single-user, single-tasking: supports a single user and one task at a time.
• Single-user, multi-tasking: allows a single user to run multiple programs at the same time.
• Multi-user: supports multiple users simultaneously.
• Real-time operating systems (RTOS): designed for systems requiring immediate responses to events, common in embedded environments (e.g., industrial control systems, robotics).

Evolution of Operating Systems

• Key eras of OS development, ranging from batch processing to personal computer operating systems and networked environments.
• The concept of time-sharing, enabling simultaneous access by multiple users, had a notable impact on the evolution of operating systems.

OS Boot

• The boot process initializes computer hardware and loads the operating system into memory.
• It includes steps like Power-On Self-Test (POST), BIOS/UEFI initialization, boot loader execution, kernel loading, user space initialization, and user interface opening.
• Cold vs. warm booting differ in their starting state.

Hibernate

• Hibernation saves the contents of computer memory to disk before shutting down, allowing a quick return to the saved state when needed.

Types of boot processes

• BIOS boot, UEFI boot, network boot (PXE), fast boot/hybrid boot, secure boot, and boot from external media.
• Different types of boot processes and underlying procedures cater to different needs and system architectures.

Memory Management

• Memory management is the technique of controlling and coordinating computer memory.
• Proper memory management is important for efficiently using RAM, handling multitasking, and preventing conflicts between running programs.

Memory Hierarchy

• Memory is organized in a hierarchical structure with varying access speeds and capacities.
• Registers, cache, and main memory (RAM) are used for short-term data storage, while hard disks and SSDs are for long-term storage.
• Data transfer between levels is optimized for speed and accessibility on demand.

Address Spaces

• Process address space refers to the valid memory range a process can use during runtime.
• Kernel address space is the reserved portion of memory for the OS kernel, offering critical functionality.

Memory Allocation Strategies

• Memory allocation strategies (fixed or dynamic partitioning) manage processes' use of memory efficiently and avoid conflicts.

Fragmentation

• Memory fragmentation refers to the waste of memory space caused by scattered unused memory blocks.

Memory Allocation Algorithms

• Algorithms, like first fit, best fit, and worst fit, handle memory allocation requests.
• These algorithms prioritize different objectives (speed, efficiency) to suit various circumstances.

Programming

• Programs consist of instructions in a language that a computer understands.
• Programming involves writing and executing instructions for use with electronic devices.

Programming Language

• A programming language is a way of communicating with computers.
• Programming languages allow complex tasks by providing standard structures, code formats, and syntax for writing instructions in high-level languages.

Compilers

• Programmers use high-level languages, as they are easier to write and understand compared to the machine's own binary language.
• Compilers translate high-level language code into machine language code, making translated content executable on a computer.

Integrated Development Environment (IDE)

• An IDE is a development tool that integrates many development tools (compiler, debugger, editor) to support programmers' ease in constructing code and eliminating errors.

Object-Oriented Programming (OOP)

• OOP is a programming paradigm that focuses on objects, which represent real-world entities, grouping both data and actions.
• OOP facilitates easier code maintenance and reusability.

Documentation

• Documentation, including both internal and external documents, is a crucial aspect of the software development lifecycle.

Algorithm Introduction

• Algorithm is a sequence of well-defined steps to solve a problem.
• Well-defined, unambiguous instructions allow successful task completion.

Algorithm (Examples)

• Examples illustrated the ordered steps to achieve specific goals.

Algorithm (Control Structures)

• Control structures (sequential, selection, iterative) govern the order and logic in which instructions are executed in an algorithm.

Flowchart (Control Structures)

• Flowcharts graphically represent algorithms using diagrams.
• The specific steps are well defined in a flowchart.

Flowchart (Examples)

• Flowchart examples illustrated how to perform particular tasks step by step.

Pseudocode

• Pseudocode uses a simpler format than flowcharts or programs for algorithm presentation and is often used to design algorithms before formal implementation.
• It can represent algorithms through short, readable, and formally-styled English.

System Development Life Cycle

• System development life cycle (SDLC) describes the different stages during the lifespan of a software product from conception to maintenance, including design, implementation, testing and maintenance.
• Several phases include planning (problem definition), analysis, design, implementation, testing, and integration, maintenance.
• Retirement is also an important stage in the software development life cycle.

System Analysis

• System analysis involves finding out problems and documenting requirements and defining the scope for the software to be written; ensuring that requirements are complete and valid.

System Analysis Activities

• Activities within the system analysis phase such as data gathering, requirement definition, requirement prioritizing, prototyping, validation and documentation.

Design Process

• Design transforms user requirements into a form suitable for programmers to code and implement.
• Key aspects of the design process include planning architecture, and modules.

Design Process Activities

• Crucial activities in design, such as architectural design, abstract specification, interface design, component design, data structure design, and algorithm design.

Architecture Design

• Architecture design is the abstract design that pinpoints main modules and connections.

High-Level Design

• High-level design examines how subsystems, modules, and interactions fit together in the application.

Detailed Design

• Detailed design specifics the system's logical structure and interfaces among the modules.

Implementation and Testing

• This phase converts the design into an actual application using a programming language.
• Testing is essential to ensure the app runs efficiently and addresses all issues found in the code.

Programming Languages and Compilers

• Programmers use high-level languages to write code that is easier to understand, than machine code
• Compilers translate this code into machine language code (executable binary) to run on the computer.

Integrated Development Environment (IDE)

• IDE tools help develop applications and eliminate errors easily.