Comprehensive Study Notes on Types and Components of Computer Systems

Cambridge IGCSE Information and Communication Technology Assessment

• Syllabus Context: The information provided is based on the Cambridge IGCSE Information and Communication Technology $0417/0983$ syllabus for examinations starting in $2023$.

• Assessment Structure: There are three distinct examination papers:     * Paper 1 Theory:         * Duration: $1$ hour $30$ minutes.         * Marks: $80$ marks.         * Syllabus Sections Examined: Sections $1$ through $21$.     * Paper 2 Document Production, Databases, and Presentations:         * Duration: $2$ hours $15$ minutes.         * Marks: $70$ marks.         * Syllabus Sections Examined: Sections $11$ through $16$, $17$, $18$, and $19$.         * Focus: Practical skills using various software applications.     * Paper 3 Spreadsheets and Website Authoring:         * Duration: $2$ hours $15$ minutes.         * Marks: $70$ marks.         * Syllabus Sections Examined: Sections $11$ through $16$, $20$, and $21$.         * Focus: Practical skills using various software applications.

Examination Command Words and Definitions

• Analyse: To examine in detail to show meaning, identify elements, and the relationship between them.

• Compare: To identify and/or comment on similarities and/or differences.

• Contrast: To identify and/or comment on differences.

• Define: To give a precise meaning.

• Demonstrate: To show how or to give an example.

• Describe: To state the points of a topic or give characteristics and main features.

• Discuss: To write about issue(s) or topic(s) in depth in a structured way.

• Evaluate: To judge or calculate the quality, importance, amount, or value of something.

• Explain: To set out purposes or reasons, make relationships between things evident, provide why and/or how, and support with relevant evidence.

• Give: To produce an answer from a given source or from recall/memory.

• Identify: To name, select, or recognise.

• Justify: To support a case with evidence or argument.

• State: To express in clear terms.

• Suggest: To apply knowledge and understanding to situations with a range of valid responses to make proposals or put forward considerations.

Hardware Components of Computer Systems

• Definition of Hardware: Hardware is the general term for the physical components that constitute a typical computer system.

• External Hardware Categories:     * Input Devices: Examples include the keyboard, mouse, and camera.     * Output Devices: Examples include the monitor, printer, and plotter.

• Internal Hardware Devices:     * Motherboard:         * A printed circuit board (PCB) found in all computers.         * Acts as a 'hub' for connecting other computer devices.         * Allows the processor and other hardware to function and communicate.         * Constructed from non-conductive material (e.g., hard plastic) with printed layers of copper or aluminum for circuits.         * Contains sockets and slots for connecting additional components.     * Central Processing Unit (CPU)/Processor:         * An electronic circuit board that executes instructions from computer programs.         * Arithmetic and Logic Unit (ALU): Carries out arithmetic and logical operations.         * Control Unit (CU): Decodes and executes instructions.     * Random Access Memory (RAM):         * An internal chip for temporary data storage during application runtime.         * Is volatile/temporary memory; contents are lost when power is turned off.         * Can be written to and read from.         * Stores data, files, or parts of the operating system currently in use.     * Read-Only Memory (ROM):         * Used for permanent information storage, such as system configuration data.         * Is non-volatile memory; information is retained when power is turned off.         * Cannot be altered; it is read-only.     * Graphics Card:         * Sends graphical information to video display devices (monitor, television, projector).         * Includes its own processing unit, memory unit (usually RAM), and a cooling mechanism (heat sink).     * Sound Card:         * Integrated circuit board allowing the computer to produce sound through speakers or headphones.         * Facilitates recording via microphone and manipulation of audio files.     * Internal Storage (HDD and SSD):         * Hard Disk Drive (HDD): Magnetic storage used for data, system software, and applications.         * Solid-State Drive (SSD): Newer storage technology replacing HDDs in many computers and tablets; performs the same function as HDDs.     * Network Interface Card (NIC):         * Allows devices to connect to a network (e.g., the Internet) via wired or wireless means.         * Each NIC is hard-coded with a unique MAC (Media Access Control) address.

Software Classifications

• Definition of Software: The programs that control the computer system and process data. Divided into Application software and System software.

• Applications Software: Programs designed to perform specific tasks for the user.     * Word Processing: Manipulates text documents (essays, reports). Features include spell checkers, thesaurus, and text formatting tools.     * Spreadsheet: Organizes numerical data in a grid of lettered columns and numbered rows. Uses cells (e.g., $B6$) and formulas for calculations and modeling.     * Database Management System (DBMS): Organizes and analyzes data in tables (rows = records; columns = fields). Supports queries and reporting.     * Control and Measurement Software: Interfaces with sensors to measure physical quantities (temperature) or control processes (opening valves in chemical plants).     * Audio/Video/Graphics Editing: Tools to manipulate media files, such as altering track length, color correction in video, or changing pixels/vectors in images.     * Computer-Aided Design (CAD): Helps create and modify designs. Can produce $2\text{D}$ or $3\text{D}$ diagrams and estimate manufacturing costs.     * Apps and Applets: Applets are small, single-task applications (often in HTML pages). Apps are more substantial (streaming, banking).

• System Software: Programs that allow the hardware to run and facilitate user communication with the computer.     * Compiler: Translates High-Level Language (HLL) source code (e.g., Java, Python, $C++$) into machine code (object code).     * Linker: Combines multiple object files/modules produced by a compiler into a single executable program.     * Device Driver: Enables hardware (printers, mice) to communicate with the operating system. OS searches for these when devices are plugged into ports like USB.     * Operating System (OS): Background software managing basic functions (I/O operations, security, program loading, and user interface). Examples include Windows.     * Utilities: Software for specific maintenance tasks, including antivirus, backup, disk repair, file management, and disk defragmenters.

Data Representation: Analogue and Digital

• Digital Data:     * Computers use a binary format (base $2$ number system).     * Only values $0$ and $1$ are used.     * Data consists of discrete, discontinuous values.

• Analogue Data:     * Physical data found in the real world.     * Changes smoothly from one value to the next without discrete steps.

• Conversion Hardware:     * Analogue to Digital Converter (ADC): Converts real-world analogue signals into digital data for computer processing.     * Digital to Analogue Converter (DAC): Converts digital output from a computer into analogue signals to control hardware like motors.