CompTIA A+ Exam > CompTIA A+ Notes > Core 1 > Cheatsheet: Peripheral Devices
Cheatsheet: Peripheral Devices
1. Input Devices
1.1 Keyboard Types
| Type | Description |
|---|---|
| Wired | USB or PS/2 connection; no batteries required; reliable connection |
| Wireless | Bluetooth or RF (2.4 GHz); requires batteries; uses USB dongle or native Bluetooth |
| Mechanical | Individual switches per key; tactile feedback; popular with gamers and typists |
| Membrane | Rubber dome switches; quieter; less expensive; shorter lifespan |
1.2 Mouse/Pointing Devices
| Device | Characteristics |
|---|---|
| Optical Mouse | LED light sensor; works on most surfaces; no moving parts; standard resolution 800-1600 DPI |
| Laser Mouse | Laser sensor; higher precision; works on glass; resolution up to 16000+ DPI |
| Trackball | Stationary base with rolling ball; less desk space; reduces wrist movement |
| Touchpad | Capacitive surface; built into laptops; multi-touch gestures supported |
| Stylus/Digitizer | Pen input on tablet or touchscreen; pressure-sensitive levels; active or passive types |
1.3 Scanners
| Type | Details |
|---|---|
| Flatbed | Document placed on glass surface; CCD or CIS sensor; resolution measured in DPI (300-4800) |
| Sheet-fed | Document fed through rollers; used for high-volume scanning; ADF (Automatic Document Feeder) |
| Handheld | Portable scanning; lower resolution; used for barcodes or small documents |
| Drum | High-end professional use; superior quality; documents mounted on rotating drum |
1.4 Webcams and Microphones
- Webcam: USB connection; 720p, 1080p, or 4K resolution; built-in or external; 30-60 fps standard
- Microphone types: Dynamic (rugged, no power needed), Condenser (requires power, studio quality), USB (digital, plug-and-play)
- Connection types: 3.5mm jack (analog), USB (digital), XLR (professional audio)
- Polar patterns: Omnidirectional (all directions), Cardioid (front-focused), Bidirectional (front and back)
1.5 Biometric Devices
| Type | Description |
|---|---|
| Fingerprint Scanner | Capacitive or optical sensor; integrated in laptops/phones; matches fingerprint patterns |
| Retina Scanner | Scans blood vessel patterns in back of eye; high accuracy; requires close proximity |
| Iris Scanner | Scans colored ring around pupil; works at greater distance than retina; near-infrared light |
| Facial Recognition | Camera-based; maps facial features; Windows Hello compatible; 2D or 3D |
| Voice Recognition | Analyzes voice patterns; microphone input; can be defeated by recordings |
1.6 Game Controllers and VR
- Game controllers: USB or wireless; DirectInput or XInput standards; force feedback/rumble
- Flight sticks/joysticks: Analog input; multiple axes; throttle control; programmable buttons
- VR headsets: HDMI/DisplayPort video; USB for tracking; external sensors or inside-out tracking; 90-120 Hz refresh rate
- Motion controllers: 6DOF (six degrees of freedom); accelerometers and gyroscopes; wireless connectivity
2. Output Devices
2.1 Display Types
| Technology | Characteristics |
|---|---|
| LCD (TN) | Twisted Nematic; fast response time (1-5ms); poor viewing angles; lower cost; 6-bit color |
| LCD (IPS) | In-Plane Switching; excellent color accuracy; wide viewing angles (178°); slower response; 8-bit color |
| LCD (VA) | Vertical Alignment; high contrast ratios; better blacks than IPS; moderate viewing angles and response |
| LED | LCD with LED backlighting; edge-lit or direct-lit; lower power consumption; thinner panels |
| OLED | Organic LED; self-emissive pixels; true blacks; infinite contrast; risk of burn-in; expensive |
2.2 Display Specifications
| Specification | Details |
|---|---|
| Resolution | 1920×1080 (FHD), 2560×1440 (QHD), 3840×2160 (4K UHD), 7680×4320 (8K) |
| Refresh Rate | 60Hz (standard), 75Hz, 120Hz, 144Hz, 240Hz (gaming); measured in Hertz |
| Response Time | 1-5ms (gaming), 5-8ms (general); gray-to-gray (GTG) measurement; lower is better |
| Brightness | Measured in cd/m² or nits; 200-300 nits (standard), 400-600 nits (HDR), 1000+ nits (peak HDR) |
| Contrast Ratio | 1000:1 (standard LCD), 3000:1 (VA panel), infinite (OLED); static vs dynamic |
| Aspect Ratio | 16:9 (standard), 16:10 (productivity), 21:9 (ultrawide), 32:9 (super ultrawide) |
2.3 Display Connectors
| Connector | Specifications |
|---|---|
| VGA (DB15) | Analog; 15-pin D-sub; max 2048×1536; legacy; no audio; blue connector |
| DVI-D | Digital only; single-link (1920×1200) or dual-link (2560×1600); no audio |
| DVI-I | Integrated analog and digital; compatible with VGA adapters; no audio |
| HDMI 1.4 | 4K at 30Hz; ARC (Audio Return Channel); 10.2 Gbps bandwidth |
| HDMI 2.0 | 4K at 60Hz; 18 Gbps bandwidth; HDR support; 32 audio channels |
| HDMI 2.1 | 8K at 60Hz or 4K at 120Hz; 48 Gbps bandwidth; eARC; VRR (Variable Refresh Rate) |
| DisplayPort 1.2 | 4K at 60Hz; 21.6 Gbps bandwidth; daisy-chaining support; locking connector |
| DisplayPort 1.4 | 8K at 60Hz or 4K at 120Hz; 32.4 Gbps bandwidth; HDR support; DSC (Display Stream Compression) |
| Thunderbolt 3/4 | USB-C connector; DisplayPort Alt Mode; 40 Gbps; supports dual 4K or single 5K displays |
2.4 Printers
2.4.1 Inkjet Printers
- Thermal inkjet: Heats ink to create bubbles that spray droplets; HP and Canon use this method
- Piezoelectric: Uses crystals that vibrate to spray ink; Epson uses this method
- Print head: Contains nozzles; can be integrated with cartridge or separate
- Cartridges: Individual color or combined; CMYK (Cyan, Magenta, Yellow, Black)
- Resolution: 1200×1200 DPI to 4800×1200 DPI; measured in dots per inch
- Speed: 10-20 PPM (pages per minute) black, 5-15 PPM color
- Maintenance: Print head cleaning, alignment, nozzle check
2.4.2 Laser Printers
| Component | Function |
|---|---|
| Drum/Imaging Drum | Photosensitive cylinder; holds electrostatic image; can be integrated with toner or separate |
| Toner Cartridge | Contains powdered ink (toner); CMYK for color printers; rated for page yield (3K, 10K pages) |
| Fuser Assembly | Heats and pressurizes toner onto paper; operating temperature 180-200°C (356-392°F) |
| Transfer Belt/Roller | Transfers toner from drum to paper; applies positive charge to paper |
| Pickup Roller | Grabs paper from tray; rubber material wears over time |
| Separation Pad | Prevents multiple sheets from feeding; cork or rubber material |
2.4.3 Laser Printing Process (7 Steps)
- Processing: Raster image processor (RIP) converts data to bitmap
- Charging: Primary corona wire or charge roller applies -600V to drum
- Exposing: Laser beam discharges areas to be printed (reduces to -100V)
- Developing: Toner (-600V charge) attracted to exposed areas (-100V) on drum
- Transferring: Transfer corona wire or roller (+600V) pulls toner from drum to paper
- Fusing: Heat (180-200°C) and pressure melt toner onto paper permanently
- Cleaning: Cleaning blade removes residual toner; erase lamp neutralizes drum charge
2.4.4 Thermal Printers
- Direct thermal: Heat-sensitive paper darkens when heated; used for receipts; fades over time
- Thermal transfer: Ribbon melts ink onto paper; more durable; used for labels and barcodes
- No ink or toner required (direct thermal); ribbon required (thermal transfer)
- Print head contains heating elements; resolution 203-600 DPI
- Maintenance: Clean print head regularly; check for debris
2.4.5 Impact Printers
- Dot matrix: Print head with 9 or 24 pins strikes ribbon against paper
- Can print carbon copies (multi-part forms); noisy operation
- Low print quality; low operating cost; 240-360 DPI resolution
- Ribbon cartridge needs replacement; pin heads wear out
2.4.6 3D Printers
| Technology | Description |
|---|---|
| FDM (Fused Deposition Modeling) | Melts plastic filament; layer by layer extrusion; PLA, ABS, PETG materials; most common type |
| SLA (Stereolithography) | UV laser cures liquid resin; high detail and resolution; requires post-processing and support removal |
| SLS (Selective Laser Sintering) | Laser fuses powder material; no support structures needed; industrial use; nylon or metal powder |
2.5 Speakers and Audio Output
- Speaker configuration: 2.0 (stereo), 2.1 (stereo with subwoofer), 5.1 (surround), 7.1 (enhanced surround)
- Connections: 3.5mm jack (analog), USB (digital), Bluetooth (wireless), optical/TOSLINK (digital)
- Impedance: 4, 6, or 8 ohms; must match amplifier specifications
- Wattage: RMS (continuous power) vs peak power; higher wattage means louder volume potential
- Frequency response: 20 Hz - 20 kHz (human hearing range); subwoofer handles 20-200 Hz
3. Multimedia Devices
3.1 Optical Drives
| Type | Capacity & Speed |
|---|---|
| CD-ROM | 700 MB; read-only; 1× speed = 150 KB/s; up to 52× speeds available |
| CD-R | 700 MB; write once; 1×-52× write speeds |
| CD-RW | 700 MB; rewritable up to 1000 times; slower than CD-R |
| DVD-ROM | Single-layer 4.7 GB, dual-layer 8.5 GB; 1× speed = 1.35 MB/s; up to 16× speeds |
| DVD±R | 4.7 GB (SL) or 8.5 GB (DL); write once; DVD-R and DVD+R are competing formats |
| DVD±RW | 4.7 GB; rewritable up to 1000 times; DVD-RW and DVD+RW formats |
| Blu-ray (BD-ROM) | Single-layer 25 GB, dual-layer 50 GB, quad-layer 128 GB; 405nm blue-violet laser |
| BD-R | 25 GB (SL), 50 GB (DL), 100 GB (XL); write once; 1× speed = 4.5 MB/s |
| BD-RE | 25 GB, 50 GB, 100 GB; rewritable; same speeds as BD-R |
3.2 Flash Memory and Card Readers
| Format | Characteristics |
|---|---|
| SD (Secure Digital) | 32×24×2.1mm; up to 2 GB; FAT16 file system; legacy format |
| SDHC | High Capacity; 4 GB to 32 GB; FAT32 file system; Class 2, 4, 6, 10 speed ratings |
| SDXC | Extended Capacity; 64 GB to 2 TB; exFAT file system; UHS-I, UHS-II, UHS-III speeds |
| microSD/microSDHC/microSDXC | 15×11×1mm; same capacities as SD equivalents; used in phones and tablets; adapter available |
| CompactFlash (CF) | 43×36×3.3mm; up to 512 GB; Type I (3.3mm) and Type II (5mm); PATA/IDE interface; professional cameras |
| Memory Stick | Sony proprietary; various versions (Pro, Duo, Micro); up to 32 GB; less common |
| xD-Picture Card | Olympus/Fujifilm; 20×25×1.7mm; up to 2 GB; obsolete format |
3.2.1 SD Card Speed Classes
- Class 2: 2 MB/s minimum write speed
- Class 4: 4 MB/s minimum write speed
- Class 6: 6 MB/s minimum write speed
- Class 10: 10 MB/s minimum write speed
- UHS-I (U1): 10 MB/s; max bus speed 104 MB/s
- UHS-I (U3): 30 MB/s; supports 4K video recording
- UHS-II: 312 MB/s max bus speed; additional row of pins
- Video Speed Class: V6, V10, V30, V60, V90 (number indicates MB/s)
3.3 Digital Cameras and Capture Cards
- Digital cameras: USB or SD card transfer; resolution measured in megapixels; RAW or JPEG formats
- Webcam vs digital camera: Webcams designed for streaming; cameras for high-quality stills/video
- Capture cards: PCIe or USB; HDMI/SDI input; captures video from external sources (consoles, cameras)
- Capture card specs: 1080p60, 4K30, 4K60; passthrough support; hardware vs software encoding
4. Storage Peripherals
4.1 External Storage Types
| Type | Details |
|---|---|
| External HDD | USB 3.0/3.1; 2.5" (portable, bus-powered) or 3.5" (desktop, AC powered); 1-18 TB capacity |
| External SSD | USB 3.1/3.2, Thunderbolt; faster than HDD; 250 GB - 8 TB; no moving parts |
| NAS (Network Attached Storage) | Network connection via Ethernet; multiple drive bays; RAID support; remote access capability |
| USB Flash Drive | USB-A or USB-C; 8 GB - 2 TB; portable; USB 2.0 (480 Mbps) to USB 3.2 (20 Gbps) |
| Tape Drive | LTO (Linear Tape-Open); LTO-9 = 18 TB native, 45 TB compressed; backup and archival; sequential access |
4.2 External Drive Interfaces
| Interface | Speed |
|---|---|
| USB 2.0 | 480 Mbps (60 MB/s); backward compatible; Type-A connector |
| USB 3.0/3.1 Gen 1 | 5 Gbps (625 MB/s); blue port; SuperSpeed; Type-A or Type-C |
| USB 3.1 Gen 2 | 10 Gbps (1.25 GB/s); SuperSpeed+; Type-C connector |
| USB 3.2 Gen 2×2 | 20 Gbps (2.5 GB/s); requires USB-C; dual-lane operation |
| eSATA | 6 Gbps (750 MB/s); external SATA; requires separate power; less common now |
| Thunderbolt 2 | 20 Gbps; Mini DisplayPort connector; daisy-chain up to 6 devices |
| Thunderbolt 3 | 40 Gbps; USB-C connector; PCIe and DisplayPort support; 15W-100W power delivery |
| Thunderbolt 4 | 40 Gbps; USB-C; stricter certification; dual 4K or single 8K display; 40 Gbps PCIe requirement |
5. Connection Standards
5.1 USB Standards Comparison
| Standard | Speed |
|---|---|
| USB 1.1 | 12 Mbps (Full Speed); legacy keyboards/mice |
| USB 2.0 | 480 Mbps (High Speed); black connector; 5V, 500mA power |
| USB 3.0 (3.1 Gen 1) | 5 Gbps (SuperSpeed); blue connector; 5V, 900mA power |
| USB 3.1 Gen 2 | 10 Gbps (SuperSpeed+); teal/red connector or USB-C |
| USB 3.2 Gen 1 | 5 Gbps; rebranded USB 3.0 |
| USB 3.2 Gen 2 | 10 Gbps; rebranded USB 3.1 Gen 2 |
| USB 3.2 Gen 2×2 | 20 Gbps; USB-C only; dual-lane operation |
| USB4 | 40 Gbps; USB-C connector; Thunderbolt 3 compatible; tunnels PCIe and DisplayPort |
5.2 USB Connector Types
| Connector | Description |
|---|---|
| Type-A | Rectangular; host-side connector; USB 1.1 through 3.2; not reversible |
| Type-B | Square with beveled corners; printer-side; USB 2.0 version; less common on modern devices |
| Mini-USB | 5-pin; older mobile devices and cameras; mostly obsolete |
| Micro-USB Type-B | 5-pin; Android phones (pre-2017); external hard drives; not reversible |
| Micro-USB 3.0 | 10-pin; dual connector design; external hard drives; backward compatible with Micro-USB 2.0 |
| Type-C | 24-pin; reversible; USB 3.1/3.2/4 and Thunderbolt 3/4; power delivery up to 100W |
5.3 Wireless Connection Standards
5.3.1 Bluetooth
| Version | Characteristics |
|---|---|
| Bluetooth 2.0 + EDR | Enhanced Data Rate; 3 Mbps; 10m range (Class 2); legacy devices |
| Bluetooth 3.0 + HS | High Speed; 24 Mbps (via 802.11); backward compatible |
| Bluetooth 4.0 | Low Energy (BLE); 1 Mbps; fitness trackers and IoT; coin cell battery operation |
| Bluetooth 4.2 | IoT enhancements; improved privacy; IP connectivity |
| Bluetooth 5.0 | 2 Mbps speed; 240m range (open air); 4× range or 2× speed vs 4.2 |
| Bluetooth 5.1/5.2 | Direction finding; LE Audio; improved coexistence with WiFi |
5.3.2 Wireless USB and RF
- 2.4 GHz RF: Proprietary wireless; USB dongle required; 10m range; keyboards, mice, presentation remotes
- Wireless USB (WUSB): 480 Mbps at 3m, 110 Mbps at 10m; UWB (Ultra-Wideband); mostly obsolete
- Pairing: Bluetooth requires pairing process; RF dongles pre-paired at factory
- Interference: 2.4 GHz shared with WiFi; can cause connectivity issues
5.4 Legacy Connectors
| Connector | Details |
|---|---|
| PS/2 | 6-pin Mini-DIN; purple (keyboard), green (mouse); AT/AT2 standard; no hot-swap; 12 Kbps |
| Serial (RS-232) | DB9 (9-pin) male; COM ports; modems and legacy equipment; 115.2 Kbps max |
| Parallel (LPT) | DB25 (25-pin) female; printer port; 8-bit parallel data; 2 Mbps; IEEE 1284 standard |
| Game Port (MIDI) | DB15 (15-pin) female; joysticks and MIDI devices; 2-axis, 4-button support; obsolete |
6. Peripheral Installation and Troubleshooting
6.1 Installation Methods
- Plug and Play (PnP): Automatic device detection and driver installation; USB, Bluetooth devices
- Driver installation: Manual driver install from disc or download; device-specific software
- Windows: Device Manager shows installed devices; driver updates available through Windows Update
- Hot-swappable: USB, Thunderbolt, eSATA; connect/disconnect without shutdown
- Non-hot-swappable: PS/2 ports; require system shutdown before connection changes
6.2 Common Printer Issues
| Issue | Causes/Solutions |
|---|---|
| Paper Jams | Check pickup rollers, worn separation pad, wrong paper type, overfilled tray, debris in paper path |
| Faded Prints | Low toner/ink, eco/draft mode enabled, clogged nozzles (inkjet), worn drum (laser) |
| Streaks/Lines | Dirty drum, scratched drum, debris on corona wire, clogged inkjet nozzles, print head alignment |
| Ghosting | Faulty fuser assembly, incorrect paper weight setting, worn drum, residual toner not cleaned |
| Toner Not Fusing | Failed fuser assembly, incorrect paper type, fuser temperature too low |
| Blank Pages | Empty cartridge, print head disconnected, corona wire failure, drum not charging |
| Smudging | Fuser not heating properly, wrong paper type, excess toner, dirty fuser rollers |
| Vertical Lines | Scratched drum, dirty corona wire, damaged fuser roller |
| Garbled Prints | Wrong printer driver, corrupted print spooler, incorrect page description language (PCL vs PostScript) |
6.3 Printer Maintenance
- Laser: Replace toner cartridge, clean corona wires, replace drum (separate or with toner), replace fuser assembly, clean pickup rollers with isopropyl alcohol
- Inkjet: Replace ink cartridges, run print head cleaning cycle, perform nozzle check, align print heads, clean paper feed rollers
- Maintenance kits: Laser printer kits include fuser, transfer roller, pickup rollers, separation pads; rated by page count (100K, 200K pages)
- Calibration: Color calibration for accurate color reproduction; automatic or manual process
6.4 Display Troubleshooting
| Issue | Causes/Solutions |
|---|---|
| No Display | Check cable connections, verify input source selected, test with different cable/port, check power |
| Flickering | Loose cable, incompatible refresh rate, failing backlight, electromagnetic interference |
| Dim Display | Low brightness setting, failing backlight, inverter failure (CCFL), power saving mode enabled |
| Dead Pixels | Stuck pixels (fixable with software), dead pixels (hardware failure); check manufacturer warranty |
| Incorrect Resolution | Wrong display driver, cable limitations (VGA max resolution), GPU settings, extended vs duplicate mode |
| Color Issues | Loose cable pins (VGA/DVI), wrong color depth setting, failing panel, color calibration needed |
| Image Burn-in | OLED/plasma displays; static images displayed too long; use screen savers, pixel shift features |
6.5 Peripheral Troubleshooting
- Device not recognized: Check cable connection, try different USB port, update drivers, check Device Manager for errors
- Intermittent connection: Loose cable, damaged port, wireless interference, low battery (wireless devices)
- Slow performance: USB 2.0 port used instead of 3.0, cable quality issues, insufficient bus power, driver issues
- Audio issues: Wrong playback device selected, muted output, driver problems, disabled audio device
- Scanner not working: Check TWAIN driver installation, verify scan software compatibility, USB connection issues
- External drive not detected: Insufficient power (USB), drive not initialized, driver missing, faulty enclosure
6.6 Driver Management
- Device Manager: Windows tool to view, update, disable, uninstall device drivers; error codes indicate issues
- Driver sources: Windows Update, manufacturer website, Windows built-in drivers, driver disc
- Driver rollback: Revert to previous driver version if update causes issues
- Unsigned drivers: Windows security warning; may cause system instability; disable driver signature enforcement for installation
- Generic vs specific: Generic drivers provide basic functionality; manufacturer drivers enable all features
7. KVM and Docking Stations
7.1 KVM Switches
- KVM: Keyboard, Video, Mouse switch; controls multiple computers with single set of peripherals
- Switching methods: Physical button, keyboard hotkey (Scroll Lock, Scroll Lock, number), remote switching
- Connections: VGA, DVI, HDMI, DisplayPort for video; USB or PS/2 for keyboard/mouse
- Port configurations: 2-port, 4-port, 8-port, 16-port models available
- Features: Audio switching, USB peripheral sharing, multi-monitor support, rack-mountable options
7.2 Docking Stations
| Type | Characteristics |
|---|---|
| Proprietary Dock | Manufacturer-specific connector; laptop slides into dock; charges laptop; full port replication |
| USB-C Dock | Universal USB-C connection; DisplayPort Alt Mode required; 60W-100W power delivery; multi-platform |
| Thunderbolt Dock | 40 Gbps bandwidth; PCIe support; dual 4K displays; daisy-chaining; charges laptop up to 100W |
| USB 3.0 Dock | 5 Gbps limitation; DisplayLink technology for video; separate power adapter usually required |
7.3 Port Replicators vs Docking Stations
- Port replicator: Simpler device; expands available ports; does not charge laptop; lower cost
- Docking station: Full-featured; charges laptop; additional ports; may include drive bays; higher cost
- Common dock ports: USB-A, USB-C, HDMI, DisplayPort, Ethernet (Gigabit), 3.5mm audio, SD card reader
- Video limitations: USB 3.0 docks limited to 1-2 displays; Thunderbolt supports more displays at higher resolutions
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Apr 20, 2026 Last updated
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