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BSIT Course Material: Input, Output, and Storage (Notes)

Keyboard

  • Key concepts:
    • Keyboard types and layout
    • QWERTY layout as standard reference
    • Key groups:
    • Function keys: F1–F12
    • Toggle keys: Caps Lock, Num Lock, Scroll Lock
    • Modifier keys: Shift, Ctrl, Alt, AltGr
    • Positional keys: Esc, Enter, Backspace, Tab, etc.
    • Example layout elements from the transcript:
    • Top row: Esc, F1–F12
    • Alphanumeric area: keys like 1, 2, …, 0, A–Z
    • Punctuation and symbols: @ # $ % ^ & * ( ) _ + etc.
  • Significance:
    • Keyboard input is the primary human-computer interaction method for text and commands.
    • Modifier keys enable combined key actions (shortcuts).
  • Connections to practice:
    • Understanding keyboard anatomy helps troubleshoot unresponsive keys or stuck keys.
    • Knowledge of layout assists in configuring languages and regional keyboards.

Specialty keyboards

  • Types listed:
    • Wireless keyboards (Bluetooth)
    • Infrared keyboards
    • Ergonomic keyboards
    • Bilingual keyboards
    • Virtual/on-screen keyboards
  • Features:
    • Wireless connectivity eliminates cords; may require pairing and battery management.
    • Infrared and Bluetooth differ in range, interference considerations, and compatibility.
    • Ergonomic designs aim to reduce strain during long typing sessions.
    • On-screen keyboards provide input without physical keys, useful for touch devices or accessibility.
  • Example use cases:
    • A programmer using a Bluetooth keyboard at a standing desk for long coding sessions.
    • A multilingual user selecting bilingual keyboard layouts for frequent language switching.

Pointing devices

  • Main types:
    • Mouse: mechanical (ball) or optical; corded or cordless
    • Trackball
    • Touchpad
    • Touch screen
    • Joystick
  • Key ideas:
    • Precision input via physical pointers or touch interfaces.
    • Input method affects ergonomics and productivity depending on task (e.g., 2D design vs. navigation).
  • Practical notes:
    • Optical mice rely on light sensors instead of a ball; fewer moving parts and less maintenance.
    • Trackballs stay stationary; useful in constrained spaces.

Drawing tablet

  • Tool: drawing tablet with an inkless stylus
  • Purpose: create digital artwork or hand-drawn input that maps to the screen
  • Significance: enables artists to transfer traditional drawing skills to digital media with pressure sensitivity in some models

Sensory input devices

  • List:
    • Global Positioning System (GPS)
    • Accelerometer
    • Compass
    • Gyroscope
  • Use cases:
    • GPS for location-aware applications
    • Accelerometer for motion sensing (e.g., mobile devices)
    • Compass for directional data
    • Gyroscope for orientation
  • Relevance: sensors expand how computers interpret real-world context

Scanning devices

  • Purpose: digitize hard copy documents
  • Core technology:
    • Uses photosensitive charge-coupled device (CCD)
  • Types of scanners:
    • Flatbed
    • Document feeder
    • Bar code reader
    • Business card scanner
  • Significance: scanners convert physical media into editable digital formats

Other input devices

  • Types:
    • Magnetic card reader
    • Optical mark recognition (OMR)
    • Magnetic ink character recognition (MICR)
    • Radio frequency (RF) ID chip
    • Biometric authentication devices:
    • Fingerprint scanner
    • Facial recognition software and camera
    • Retina scanner
  • Relevance: adds security, data capture, and automation in workflows

Capture devices

  • Examples:
    • Digital camera
    • Digital video camera
    • Web camera (Webcam)
  • Notes:
    • Capture devices convert real-world images into digital data for storage and processing

Audio input devices

  • Components:
    • Audio adapter (sound card)
    • Microphone
  • Software aids:
    • Voice recognition software
    • Speech recognition software
  • Use cases:
    • Voice commands, dictation, voice-controlled apps

Display screen and pixels

  • Display purpose: provide information to a human user
  • Pixel concept: an individual dot on the display
  • Important metric: resolution is expressed as the number of horizontal and vertical pixels
  • LaTeX note:
    • \text{Resolution} = (\text{horizontal pixels},\; \text{vertical pixels}) = (H, V)
    • Example: 1024 \times 768 pixels

Current monitor technologies

  • Technologies:
    • Liquid Crystal Display (LCD)
    • Types: Active vs. Passive Matrix
    • Light-Emitting Diode (LED)
    • Organic LED (OLED)
    • E-paper
    • Digital/smart whiteboard
    • Digital projector
  • CRT (Cathode Ray Tube): legacy technology
    • Large vacuum tube; electron guns light up phosphors (red/green/blue triads)
  • Significance: different technologies affect color, contrast, response time, and power consumption

Resolution and aspect ratio

  • Definitions:
    • Vertical resolution: number of pixels vertically
    • Horizontal resolution: number of pixels horizontally
    • Aspect ratio: ratio of width to height, e.g., 4:3\quad \text{or}\quad 16:9
  • Example: a display with 1600\times 900 has aspect ratio \frac{1600}{900} = 1.78 \approx 16:9
  • Note: LCD/LED displays look best at native resolution

Monitor performance measures

  • Refresh rate: number of times per second each pixel is refreshed; critical for CRTs to avoid flicker
  • Color depth: number of bits per pixel describing color; common values: 32\text{-bit} or 16\text{-bit}

Display adapter

  • Role: hardware that enables the OS to communicate with the monitor
  • Placement:
    • Built into the motherboard or as a separate expansion card
  • Memory: display adapters may have their own memory
  • Driver requirement: requires a device driver in the OS to function

Printers: general factors

  • Decision criteria:
    • Initial cost
    • Per-page cost (consumables)
    • Resolution (dots per inch, DPI)
    • Speed
    • Color capability
    • Paper handling
    • Interface type
    • Multiple functions (e.g., scan, copy, fax)

Printing technologies: Impact vs Non-Impact

  • Impact printers:
    • Strike an inked ribbon to transfer ink onto paper
    • Examples: dot matrix printers (still used in industrial settings for multi-part forms)
  • Non-impact printers:
    • Do not strike paper; ink or toner is deposited onto paper
    • Examples: Inkjet, Laser, Thermal, Plotter

Inkjet printers

  • Mechanism: spray liquid ink onto the page
  • Cartridges: typically separate color cartridges (CMYK: cyan, magenta, yellow, black)
  • Pros: low initial cost; good photo printing capabilities on many models
  • Cons: ink can be expensive; variable color accuracy depending on model and media

Laser printers

  • Mechanism: uses powdered toner
  • Capabilities: can be color or black-and-white
  • Pros: higher per-page efficiency; faster; lower cost per page for high volumes
  • Cons: higher initial cost than inkjets
  • Printing process (conceptual):
    • Drum is negatively charged
    • A laser neutralizes charge in selected areas, causing toner to cling to those areas
    • Paper is charged so toner transfers to paper
    • Fuser heats the paper, melting toner into the paper
  • Note: provides typically better text quality and speed for business printing

Printer type comparison (summary)

  • Dot Matrix (impact):
    • Initial cost: medium
    • Per-page cost: inexpensive
    • Resolution: poor
    • Speed: slow
    • Color: no
    • Paper handling: continuous feed; multiple-part forms
    • Use: multi-part forms, text-only printouts
  • Inkjet (non-impact):
    • Initial cost: inexpensive
    • Per-page cost: expensive
    • Resolution: good
    • Speed: medium
    • Color: yes
    • Paper handling: single low-capacity tray
    • Use: photo printing, home use
  • Laser (non-impact):
    • Initial cost: expensive
    • Per-page cost: inexpensive
    • Resolution: good
    • Speed: fast
    • Color: some models
    • Paper handling: multiple high-capacity trays (some models)
    • Use: business printing, high-volume printing

Specialty printers

  • Thermal printers
    • Direct thermal
    • Thermal wax transfer
    • Thermal dye transfer
  • Plotter
    • Used for large-scale vector graphics and architectural drawings

Storage devices: overview

  • Storage taxonomy:
    • Primary storage: memory (RAM)
    • Secondary storage: disks and solid-state drives (SSDs)
  • Evaluations of storage:
    • Capacity
    • Cost
    • Access speed
    • Interface
    • Media type
    • Portability
    • Removability

File storage vocabulary

  • File: named collection of bits representing a single object
  • Folder: logical organizing unit for files
  • Volume: physical storage device or portion assigned a drive letter
  • Drive: physical storage device or the mechanical parts that spin a disk to read/write data
  • Disk: spinning platter that holds data

Hard Disk Drive (HDD) structure

  • HDD description: mechanical storage drive with stacked platters
  • Data storage: binary form via magnetic polarity changes
  • Key concepts:
    • Track: concentric ring on one side of one platter
    • Sector: section of a track
    • Platter: each platter is two-sided; number of heads = number of platters × 2
    • Cylinder: collection of all tracks at a given position across all platters
  • Real-world takeaway: HDDs store data magnetically and organize data into tracks/sectors; performance depends on seek time, rotational speed, and data density

Optical drives and discs

  • Optical media types: CDs, DVDs, Blu-ray discs
  • How they work: read/write using patterns of reflectivity on disc surface
  • Disc formats:
    • CD-ROM (read-only)
    • CD-R (write once)
    • CD-RW (rewriteable)
    • DVD-ROM (read-only)
    • DVD+R, DVD-R (write-once)
    • DVD+RW, DVD-RW (rewriteable)
    • Blu-ray ROM (read-only, high-definition media)
    • BD-R (write once), BD-RW (rewriteable)
  • Physical characteristics:
    • Single-sided/double-sided
    • Single-layer/double-layer
  • Capacities:
    • CD-ROM: 650\text{ to }900\,\text{MB}
    • CD-R: 650\text{ to }900\,\text{MB}
    • CD-RW: 650\text{ to }900\,\text{MB}
    • DVD-ROM: 4.7\,\text{GB per side and per layer}
    • DVD+R/DVD-R: 4.7\,\text{GB per side and per layer}
    • DVD+RW/DVD-RW: 4.7\,\text{GB per side and per layer}
    • Blu-ray-ROM (BD-ROM): 25\text{ to }128\,\text{GB, depending on number of layers}
    • BD-R/BD-RW: 25\text{ to }128\,\text{GB, depending on number of layers}
  • Notes:
    • DVD drives typically support both CD and DVD formats
    • BD drives support CDs and DVDs as well

Solid-state drives (SSDs)

  • Definition: use a form of EEPROM memory to store data
  • Form factors:
    • Small, removable USB flash drives
    • Larger SSDs designed to replace HDDs (SSHD is a hybrid combining HDD capacity with SSD technology)
  • Benefits: faster access times, more reliability (no moving parts) compared to HDDs

Network storage vocabulary

  • Direct-attached storage (DAS): local storage connected directly to the computer
  • Network-attached storage (NAS): storage accessed over a network
    • NAS appliance: specialized device providing storage space to network users
  • Storage-area network (SAN): network-accessed storage that appears as local storage to the user
  • Relevance: enables scalable storage for multiple users and devices across an organization

Redundancy and performance: RAID

  • RAID stands for Redundant Array of Inexpensive Disks
  • Common configurations:
    • RAID0: striping for performance (data split across disks; no redundancy)
    • RAID1: mirroring for data security (duplicate copies on separate disks)
    • RAID5: striping with parity (parity distributed across disks; balance of performance and redundancy)
  • Real-world use: improves performance and/or data protection depending on configuration

Cloud storage

  • Cloud: secure computing environment accessed online
  • Cloud storage: storage accessed from a cloud environment via internet services
  • Implications: scalability, accessibility, and potential security/privacy considerations

Troubleshooting (problem-solution outlines)

  • Keyboard issues:
    • Problem: Keyboard not responsive
    • Probable causes: connectivity, keyboard failure, debris under keys
    • Solutions: reseat connectors, try another keyboard; flip keyboard and shake or use compressed air to remove debris
    • Other: one key not working may be stuck or debris; same remedy applied
  • Mouse issues:
    • Problems: no response, cursor not moving in one direction, pointer jumps
    • Solutions: check connections, clean mouse, reboot, update display/adapter drivers if needed
  • Display issues:
    • Problems: no display or monitor lights; color tint; amber/green/blue tint
    • Solutions: check power, connections, ensure signal is reaching monitor, update display driver
  • Printer issues:
    • Problems: color issues on inkjet; laser printouts dirty or faded; smudges; toner issues; blank pages
    • Solutions: run printer cleaning utility; clean printer; adjust toner; replace cartridges; ensure page dries before handling; service if necessary
  • Sound issues:
    • Problems: no sound; low volume; no audio adapter installed; garbled sound
    • Solutions: check volume controls; verify speakers and power; reinstall audio driver; service if persists
  • Hard disk drive issues:
    • Problems: HDD not recognized; read/write errors; continuous noises
    • Causes: drive failure; loose cables; RAM-related virtual memory usage; disk surface defects
    • Solutions: check BIOS recognition; run disk check utilities (e.g., Check Disk); replace drive; add RAM if needed
  • Optical disc issues:
    • Problems: read errors; disc won’t eject; write errors
    • Causes: dirty/scratched disc; eject mechanism issues; high recording speed; CPU interference
    • Solutions: clean disc; manually eject via drive tray hole if needed; record at slower speeds; avoid multitasking during burn

Summary questions (practice)

  • 1) List three input devices and three output devices.
  • 2) How do wireless input devices communicate with the computer?
  • 3) Explain briefly how LCD and CRT technologies form screen images.
  • 4) List three types of printers and give an example of an appropriate use for each one.
  • 5) Explain how HDD and SSHD differ internally.
  • 6) Differentiate between DAS, NAS, SAN, and cloud storage.

References

  • Wiley, Computer Basics (2024)
  • ISACA (2021), Computing Fundamentals: Study Guide
  • O’Leary, D.A. et al (2021), Computing Essentials: making IT work for you (Introductory)
  • Crutcher, P.D. (2021), Essential Computer Science: A programmer’s guide to foundational concepts.