IGCSE ICT – Chapter 1 Summary (Types & Components of Computer Systems)

Hardware (physical components)
- External examples – keyboard, mouse, camera, monitor, printer, plotter
- Internal examples – motherboard, $\text{CPU}$ , RAM, ROM, graphics & sound cards, NIC, HDD & SSD
- Analogy – pages & ink of a book
Software (programs / instructions)
- Applications software – word-processing, spreadsheets, databases, CAD, video/audio editing, control & measurement, apps/applets
- System software – OS, utilities, compilers, linkers, device drivers
- Analogy – words printed on the book pages

Motherboard
- Printed-circuit hub; copper/aluminium tracks, sockets & slots
CPU / Microprocessor
- ALU (arithmetic/logic) + CU (control) + registers
- Executes program instructions
Graphics Card – GPU + RAM + heat-sink + display connectors
Sound Card – audio output (speakers/headphones), mic input, digital manipulation
Network Interface Card (NIC) – wired/wireless, unique MAC address
RAM (volatile) – temporary store for data/OS/programs in use
ROM (non-volatile) – permanent store (e.g.
BIOS/boot file), cannot be altered
HDD – magnetic platters for OS, apps, files
SSD – solid-state replacement, same purpose as HDD

Applications Software
- Word Processor – create/edit text; copy-paste, spell-check, image import
- Spreadsheet – numerical grids, formulae, graphs, modelling/“what-if”
- Database (DBMS) – tables, records, fields, queries, reports
- Graphics-editing – bitmap pixel or vector object manipulation
- Audio-editing – trim, convert formats, fade, mix, noise reduction
- Video-editing – cut/arrange clips, colour correction, transitions, titles
- CAD – 2D/3D, rotate views, dimensions, cost/structural analysis
- Control & Measurement – sensors → computer, compare → actuators
- Apps/Applets – single-task (embedded in HTML) or multi-task (smartphone)
System Software
- Compiler – HLL $\to$ machine code; source $\to$ object code
- Linker – combine object modules into single program
- Device Driver – enables hardware ↔ OS; searched automatically on plug-in
- Operating System (OS) – manages I/O, user interface, program loading, error handling, security
- Utilities – antivirus, antispyware, backup, disk repair/defrag, file mgmt, screensaver

Analogue – smooth, continuous $\infty$ possible values (e.g.
$2.5,\ 4.652$ )
Digital – discrete ${0,1}$ ; computers only understand binary
Conversion
- ADC – analogue $\to$ digital
- DAC – digital $\to$ analogue (e.g.
  motor control)

Four key internals – CPU, HDD/SSD, RAM, ROM
Peripheral Devices
- Input – keyboard, mouse, camera, mic, sensors, scanner
- Output – monitor, printer, speakers, projector, plotter
- Secondary Storage – HDD, SSD, pen-drive
Typical System Diagram – input ⇒ CPU/RAM ⇒ output + secondary storage

OS tasks – device control, load/run apps, error handling, security, logs, user interface
User Interface Types
- CLI – typed commands; flexible but steep learning, error-prone
- GUI – WIMP/icons, mouse/touch; user-friendly; needs more memory/OS
- Dialogue-based – voice commands (e.g.
  “Hey BMW…”); hands-free; noise issues
- Gesture-based – hand/finger/foot motions detected by camera/sensor; natural but limited range/gestures

Desktop
- + standard parts, cheap upgrades, better spec per , wired stable net
- – not portable, wiring clutter, need to copy files or cloud
Laptop/Notebook
- + portable, all-in-one, Wi-Fi, low power/heat
- – theft risk, limited battery, small keyboard, upgrade limits
Smartphone
- HD touch display, cameras, sensors (proximity, accelerometer), Bluetooth, flash/cloud, future OLED & Li-Fi
- + pocket size, anywhere internet, sensor-based apps
- – tiny screen/keyboard, small battery/memory, slower mobile data, theft
Tablet
- Touch screen, virtual keyboard, apps, Wi-Fi/3G/4G/5G
- + instant on, light, long battery, no heat
- – cost, limited storage/ formats, paid data plans, typing slow
Phablet – 5.1\text{''} - 7\text{''} screen, hybrid of phone+tablet

Entertainment streaming, gaming, photography/video, web & email, GPS, banking, VoIP, social media, smart-home control
Exercise 1a – identify microprocessor-controlled home devices (student task)

Artificial Intelligence (AI)
- Duplicates human decision-making; apps – language, face recognition, autonomous vehicles, robotic surgery
- Positives – safety, quality; Negatives – job loss, dependency, skill loss
Extended Reality (XR)
- AR – overlays digital info onto real world (e.g.
  Pokémon GO, AR shopping, rescue training)
- VR – immerses user in 360^{\circ} digital world; uses headsets; apps – military, education, healthcare, entertainment, engineering, heritage

RAM loses contents when power off \Rightarrow volatile
ROM retains data when power off \Rightarrow non-volatile
Smartphone screen sizes:
- phone \le 5.1\text{''} $, phablet$ 5.1\text{''}–7\text{''} $, tablet$ >7\text{''}
CPU microprocessor – control unit + ALU

NIC hard-coded MAC address like digital fingerprint; used in network fault finding
BIOS stored on ROM performs POST then loads OS into RAM
Cloud storage synchronises smartphone photos with desktop automatically
Voice assistants (Alexa/Siri) – dialogue UI; car gesture control – rotate finger to change volume

Digital data ={0,1}
Data conversion: \text{ADC}:\ \text{analogue}\to\text{digital},\ \text{DAC}:\ \text{digital}\to\text{analogue}
XR ={\text{AR},\text{VR},\text{MR}}$$