Unit 1: Digital Devices Study Guide
Overview of Digital Devices
Digital devices encompass a wide variety of technologies, ranging from high-powered organizational tools to small household controllers.
Mainframe computers are large, powerful systems used by major organizations for complex processing tasks, including statistical analysis and bulk data processing. They can handle complicated jobs quickly and support multiple users simultaneously.
Microprocessors are devices that take data as input, process it, and provide an output. They are typically used to control household appliances such as washing machines and televisions.
General examples of digital devices include personal computers (PCs), digital cameras, and home entertainment systems.
Personal Computers (PCs)
PCs are common in both homes and offices and are produced in various shapes and sizes.
Desktops:
These are non-portable computers designed to stay in one place.
They offer more space for internal components compared to laptops.
Users have the option to upgrade (make the computer better and more capable) or add additional components.
Desktops often require peripheral devices (equipment connected to and used with the computer) such as a monitor, printer, mouse, and keyboard.
All-in-one Desktops: These models combine the monitor and the PC hardware into a single unit.
Laptops:
These are portable devices (easy to carry or move) that include a built-in keyboard, screen, trackpad, and rechargeable battery.
Desktop Replacements: These are larger laptops with bigger, higher-quality screens and higher performance levels designed to mimic desktop capabilities.
Single-Board Computers (SBCs)
Single-board computers are affordable devices frequently used in education, embedded computing projects, and physical computing projects.
Embedded computing: Computing hardware fixed into position to carry out a specialist task.
Physical computing: Interactive systems that sense and respond to the physical world.
Example - Raspberry Pi Zero:
A very low-cost unit.
Uses a cheap microSD card for its storage.
Mobile and Specialist Phones
Mobile Phones:
Use a SIM card to connect to a mobile network.
SIM: Subscriber Identity Module, used to identify the subscriber to the network.
Specialist Phones:
Designed with specific features to meet particular user needs.
Features include emergency buttons linked to a list of contacts.
Accessibility features: Measured by how easy something is to use, especially for people with disabilities. Examples include:
The Alto 2 ‘talking phone’: Reads names of contacts and text messages aloud for blind or partially sighted users.
Phones with fewer, larger buttons.
Tactile keypads for better responsiveness.
Adjustable on-screen text size and colors.
Specific connections for hearing aids for deaf users.
Smartphones and Tablets
Smartphones:
Small computers with Wi-Fi and mobile connectivity for calls and internet access.
Include features from other devices: cameras, media players, and hand-held games consoles.
They run advanced operating systems and use Applications (apps) for customization (entertainment, education, business).
Virtual Keyboard: A keyboard displayed on and used via a touch screen.
Drawback: Smartphones consume more power than basic mobile phones due to their multiple features, leading to shorter battery life and a need for frequent charging.
Tablets:
Larger than smartphones but share similar features (touch screens, apps, Wi-Fi).
Some include SIM card slots for mobile network connectivity when Wi-Fi is unavailable.
Digital Cameras and Camcorders
These devices use light sensors to capture images formed by light passing through a lens.
Historically, cameras captured still images and camcorders captured moving images, but modern versions of both can usually do both.
Main Components:
Lens: A high-quality lens allows light to pass through without defects and lets the user control the amount of light, affecting the final image.
Light Sensor: Captures detail. High-quality sensors produce images with a greater number of pixels.
Image Processor: Compensates for poor lighting conditions.
Pixels and Resolution:
Digital images are made of small dots called pixels.
The sensor resolution is defined by the number of pixels captured.
Pixelated: An effect where large individual pixels become visible to the eye, creating an unclear image, often when enlarged.
Moving Images (Movies):
These are sequences of images called "frames."
High frame rates produce smooth motion, while low frame rates can appear to stutter or jump.
Television Systems
Televisions display still and moving images on a screen.
Screen Resolution:
Defined by the number of pixels used.
Stated as horizontal pixels vertical pixels (e.g., or ).
It can also be referred to by the vertical pixel count alone (e.g., , ).
UHD (Ultra High Definition):
Sometimes called 4K or 8K due to horizontal resolutions of approximately or pixels.
8K resolution makes individual pixels indistinguishable even when viewed from a close distance.
Sound Systems:
Most TVs have small, limited-quality built-in speakers because the screens are thin.
Modern TVs can connect to external sound systems or speakers with built-in amplifiers to improve audio quality.
Smart Televisions:
Use apps to download and stream content from the internet.
Stream: To play a file while it is downloading, rather than saving the whole file first.
Video and Gaming Devices
Personal Video Recorders (PVR): A device that records broadcasted content for later viewing. Frequently combined with a set-top box (STB), which receives video/audio from a broadcaster.
Blu-ray and DVD Players:
Blu-ray players can usually play DVDs, but DVD players cannot play Blu-ray disks.
Blu-ray disks store HD movies with higher quality; 4K Ultra HD Blu-ray players handle 4K content.
Games Consoles:
Designed for playing computerized video games on a screen.
Modern consoles are multifunctional, offering apps, internet access, and the ability to play music or movies via disks (DVD/Blu-ray).
Controllers: Can be wired, wireless, or use motion sensors (gestures and body movements).
Virtual Reality (VR): Uses headsets and controllers to immerse players. Real-world movements are replicated by an avatar (a figure representing a person in a virtual environment).
Handheld Games Consoles:
Provide mobile gaming but have built-in screens and less storage than full-size consoles.
Limitations: Reduced image/sound quality, reduced game complexity, and limited storylines to save storage data (values representing information).
Media Players and Personal Media Players (PMP)
Media Players: Provide video and audio to a TV via internet streaming or local/networked storage. They are controlled by remotes or smartphone apps. A Raspberry Pi Zero can be used as an affordable media player.
Personal Media Players (PMP): Compact, portable devices with local storage.
Often use solid-state flash memory, which is resilient to movement or shaking, making them ideal for traveling or exercise.
Navigation Aids
These devices calculate the best route between locations and provide updates if the route is missed.
Global Positioning System (GPS):
Uses radio signals from satellites orbiting more than above Earth to show an exact position.
It does not require internet to function, but internet is needed to update map data.
It is accurate to within .
Functionality:
They use orientation sensors (tracking $X$, $Y$, and $Z$ axes) to determine which way the device is pointing.
Maps are either stored on the device or downloaded as needed.
Sat-Nav: A satellite-based navigation system used for ships, cars, vans, and by pedestrians/cyclists.
Smartphones are increasingly replacing specialist in-car navigation aids due to available navigation apps.
Home Automation and Smart Assistants
This emerging technology is used to create "smart homes."
These devices connect and control functions in the home such as temperature and lighting.
They utilize sensors and can be controlled via smartphone apps or the internet.