ICT 4IT1 Digital Devices - Summary Notes

Assessment Structure and Availability

• Paper 1 (Written) contributes $50\%$ of the total marks; maximum $100$; duration $1\ \text{hour and } 30\ \text{minutes}$; June examination series; Paper code $4IT1/01$.

• Paper 2 (Practical) contributes $50\%$ of the total marks; maximum $100$; duration $3\ \text{hours}$; Paper code $4IT1/02$; first assessment May/June 2019; available in the June series. Paper 2 has two sections; both are required; no optional element.

Digital Devices: Overview

• Digital devices are hardware that use computers or microcontrollers. Key types include Mainframes, Servers, Supercomputers, Personal Computers (PCs), Single-Board Computers (SBCs), Mobile Devices, Tablets, Cameras, and Home entertainment systems.

Mainframe Computers

• Large, powerful systems for complex processing tasks; support many users; used by large organisations for databases, transaction processing, and critical applications. Mainframes have high memory and fast processors to handle billions of operations in real time.

Server, Supercomputer, and Related Concepts

• Server: provides a service to client programs/users; in data centers; scalable to support more users.

• Supercomputer: extremely high performance; measured in floating-point operations per second; used for scientific and high-computation tasks.

Personal Computers (PCs)

• Common in homes/offices; desktops offer upgradeability; require peripherals (monitor, printer, mouse, keyboard).

Single-Board Computers (SBCs)

• Affordable, used in education and embedded/physical computing projects; Raspberry Pi Zero as example; storage via MicroSD card; embedded computing = hardware fixed for a specialized task; physical computing = interactive systems sensing/responding to the world.

Mobile Devices: Phones and Tablets

• Mobile Phones use a SIM card; specialist phones offer emergency contacts and accessibility features (physical design, voice guide, voice commands).

• Smartphones: small computers with Wi-Fi/cell connectivity; features include cameras, media players, apps; touch screen and virtual keyboard.

• Tablets: larger than smartphones; similar features (touch screen, apps, Wi‑Fi); some have SIM slots for internet connectivity.

Cameras and Imaging

• Digital cameras/camcorders use light sensors to capture stills/movies; image quality depends on sensor, lens, image processor, and resolution.

• A good lens minimizes defects and controls light; image processors can compensate for poor lighting; digital images are made of pixels; higher-quality sensors capture more detail.

Display Resolution and Pixel Concepts

• Resolution describes pixel count; higher resolution = sharper image. Examples: $1280\times 720$ (720p), $1920\times 1080$ (1080p); UHD 4K/8K have ~$4000$ or $8000$ horizontal pixels.

Smart TVs and Convergence

• Smart TVs run apps and stream content from the internet; streaming means playing while downloading; convergence blurs device boundaries (smartphones/tablets similar in some ways).

Visual and Audio Output Systems

• Sound systems use high-quality speakers/amplifiers; connections via USB, Bluetooth, or Wi‑Fi; network streaming possible.

• Displays, speakers, and output devices may form part of home entertainment systems with stereo or surround sound.

Connectivity: Wired vs Wireless

• Wired: faster, more reliable, more secure; lower latency but cables can be costly and hazardous.

• Wireless: easy to set up, mobile, no cables, but can be less reliable and potentially less secure.

Media Support and External Drives

• Some devices need external optical drives via adapters; memory cards (SD, microSD) and optical discs (CD/DVD/Blu-ray) read/write data; diverse media support across devices.

Energy Consumption and Efficiency

• Digital devices require power; manufacturers seek lower energy use to reduce costs and environmental impact; mobile devices aim for longer battery life.

Expansion and Portability

• Some PCs allow component upgrades; smartphones/tablets may have expansion slots for flash memory; ports (USB) enable expansion.

Security Features

• Software security: password/PIN on startup; screen/keyboard lock after inactivity; lockouts after failed attempts; some devices wipe data after repeated failures.

• Stronger authentication: longer/more complex passwords; pattern PINs; biometric authentication (e.g., fingerprint, face/iris recognition).

• Physical security: security slots/locks to deter theft; secure attachments to devices.

Peripheral Devices: Input and Output

• Input peripherals send data to the computer (e.g., keyboards, mice, scanners, OCR/OMR).

• Output peripherals display or reproduce data (e.g., monitors, printers, plotters, projectors, speakers).

Key Input Devices

• Keyboard: text input; wireless or wired; shortcuts. QWERTY layout derived from typewriters.

• Pointing devices: mouse (optical/ball), tracker ball, trackpad, joystick, graphic tablet; scanners for physical documents.

• OCR/OMR: OCR converts images of text to editable text; OMR detects marked choices on forms.

Scanners and Data Capture

• Barcode scanners read linear or matrix codes; QR codes store more data and can be scanned from any angle.

• OCR/OMR advantages: faster data input, reduced human error, single processing step.

Optical/Optical Media and Storage Basics

• Optical discs: CD, DVD, Blu-ray; Blu-ray stores more data and supports 4K content; Blu-ray read/write capabilities depend on disc type.

• Hard disks (HDD) vs solid-state drives (SSD): HDD uses magnetic storage; SSD uses flash memory with no moving parts; optical discs are slower but portable and backward compatible.

• Magnetic tape is used for large-scale backups and can be rewritable and portable for off-site storage.

Storage Capacity and Data Units

• Common units (base-10): $1\ \text{KB}=10^3\text{ bytes}, 1\ \text{MB}=10^6, 1\ \text{GB}=10^9, 1\ \text{TB}=10^{12}\,.$

• Higher units: $1\ \text{PB}=10^{15}, 1\ \text{EB}=10^{18}, 1\ \text{ZB}=10^{21}, 1\ \text{YB}=10^{24}$.

Storage Media Comparisons and Examples

• HDDs: traditional storage; mechanisms involve platters, spindles, read/write heads; typical spin speeds $5400\ \text{rpm}$ or $7200\ \text{rpm}$; seek times about 4$-$15\ \text{ms}.

• SSDs: no moving parts; faster access and lower energy; more expensive per GB but increasing capacity.

• Optical discs: CD (700 MB), DVD (4.7 GB single-side, 9.4 GB double-side), Blu-ray (25 GB single, 50 GB double-side).

Data Capture and Embedded Systems in Cameras

• Embedded systems in cameras control sensor readout, exposure, and processing; data captured may be digitized, compressed, and stored.

Sensors: Types and Applications

• Types: light, moisture/humidity, temperature, proximity/distance, motion, pressure.

• Applications: input data for smart devices and cars; motion sensors in smart devices and vehicles enable automated responses.

GPS, Navigation, and Maps

• Navigation aids use GPS satellites to determine location; maps can be stored offline or downloaded; many smartphone navigation apps exist.

Personal and Home Automation

• Home automation/smart assistants connect sensors and devices via the internet to control temperature, lighting, etc.

Convergence and Modern Devices

• Convergence blurs device boundaries (smartphones and tablets are similar; smartphones gaining larger screens).

Plotters, 3D Printers, and Data Projectors

• Plotters produce high-quality CAD drawings on large media by moving a pen; some roll media.

• 3D printers create real objects by layering material; used for prototypes and complex items; can use biodegradable materials.

• Data projectors display images on screens or walls; features include resolution, brightness, zoom, and portability.

Media Players and Sound Output

• Personal media players store local media; devices may use solid-state storage for resilience.

• Speakers provide stereo or surround sound; amplifiers distribute output to multiple channels.

Printing Technologies

• Printer types: Dot Matrix, Inkjet, Laser. Dot matrix is noisy but good for copies; inkjet uses ink cartridges; laser uses toner and a rotating drum/laser; faster and often higher volume in offices.

Desktop vs Laptop: Use Case Notes

• Desktop replacements offer more powerful performance, better thermal management, and easier upgrades; laptops are portable but may have constraints on upgradability.

OCR/OMR Practical Questions (Review prompts)

• OCR reads characters; OMR detects marks on tests; these enable fast data capture with reduced manual entry.

Quick Reference (Key Terms)

• CLI, Menu-Driven, GUI, Voice Interface, Gesture Interface: major user interfaces with trade-offs in ease of use, memory usage, and interactivity.

• RAM, ROM, Virtual Memory: primary memory vs permanent storage; virtual memory expands apparent RAM via storage.

• BIOS/Operating system security: login/password/PIN, biometrics, pattern PINs.