Storage Technologies and Input & Output

Storage Concepts and Terminology

• Definition of Storage: Storage systems enable a computer to save data and programs for processing and subsequent retrieval. Storage is categorized into two primary types based on accessibility and volatility:

  • Primary Storage: These are memory locations that can be directly accessed by the computer's processing devices. They are characterized by high speed but are mostly volatile (data is lost when power is removed). Examples include:

    • Random Access Memory (RAM).

    • Registers.

    • Cache memory.

  • Secondary Storage: These locations cannot be directly accessed by processing devices. They are non-volatile (data persists without power) and are comparatively slower than primary storage. Examples include:

    • Hard Disk Drives (HDD).

    • DVD-ROMs.

    • Flash Drives.

• Data Movement and Processing: Programs, data, and files permanently saved on secondary storage must be moved to primary storage (RAM) before they can be processed by the CPU.

• Nomenclature: When the term "storage" is used alone in a computing context, it typically refers to secondary storage.

• Storage Hardware Components: Hardware used for storage consists of two distinct components:

  • Storage Medium: The physical hardware where the data is actually stored. Examples include a Hard Disk, a DVD-ROM Disc, or an SD Card.

  • Storage Device: The hardware mechanism that writes data to or reads data from the storage medium. Examples include a Hard Drive, a DVD Drive, or an SD Card Slot.

• Physical Integration of Media and Devices:

  • Removable Storage Media: These can be physically detached from the device. Examples include DVD Discs and SD Cards.

  • Sealed/Integrated Media: In some systems, the storage medium is sealed within the device and cannot be separated. Examples include Hard Disk Drives (HDD) and Solid State Drives (SSD).

Logical Representation of Data

• Definition: Logical representation refers to how data is organized, stored, and retrieved from the user's perspective, typically using names and structures rather than physical binary locations.

• Files: A collection of related bits that are assigned a name so they can be retrieved together.

  • File Extensions: File names include extensions (e.g., .jpg, .docx) that signify the file type and determine which program is used to open them.

• Folders: These are collections used to group related files, organizing them to make location and management more efficient.

• Drive Identification: Storage devices are logically identified by the operating system using letters followed by a colon, such as $C:$ and $D:$.

• User Interface Details (File Explorer/Documents): Based on common operating systems like Windows, the logical view includes various panes and layout options:

  • Panes: Preview pane, Details pane, and Navigation pane.

  • Layout Options: Extra large icons, Large icons, Medium icons, Small icons, List, Details, Tiles, and Content.

  • Organization Tools: Sort by, Group by, Add columns, and "Size all columns to fit."

  • Show/Hide Options: Item check boxes, File name extensions, and Hidden items.

  • Navigation Path Example: "This PC > Documents."

  • Specific Examples of Files/Folders:

    • Folders: Camtasia, Custom Office Templates, Hardware, Revised Files.

    • Images: $Glider.jpg$, $Hang\,Gliding.jpg$, $Para\,Gliding.jpg$.

    • Documents: $Session\,1.docx$, $Session\,2.docx$, $Session\,3A.docx$, $Session\,3B.docx$, $Session\,4.docx$, $Session\,5A.docx$, $Session\,5B.docx$, $Session\,6A.docx$, $Session\,6B.docx$, $Session\,7.docx$, and $Session\,8A.docx$.

Physical Representation of Data

• Binary Storage: All data is saved on the storage medium in the form of $0s$ and $1s$. The physical method of representing these bits varies by technology:

  • Optical Storage Systems: Data is stored optically using laser beams to create and read marks on the surface of the medium. Examples include:

    • Compact Disc (CD).

    • Digital Versatile Disc (DVD).

    • Blu-ray Disc (BD).

  • Magnetic Storage Systems: Data is stored using magnetic spots on a disk. Different magnetic alignments represent the $0s$ and $1s$. The most common example is the Hard Disk Drive (HDD).

  • Solid State Storage Systems: These utilize flash memory technology.

    • Examples: Solid State Drives (SSD), Flash drives, and SD cards.

    • Advantages: Uses less power than HDDs, has no moving parts (increasing durability), and is significantly faster than magnetic or optical technologies.

    • Disadvantage: Generally more expensive per unit of storage than HDDs.

Specialized Storage Options

• Smart Card: A small plastic card containing embedded computer circuitry, including a processor, memory, and storage. It typically stores a very small amount of data, approximately $64\,KB$ or less.

• Network Storage: A storage location that is hosted on a server and accessed through a local area network (LAN).

• Online Storage: Storage locations accessed specifically through the Internet (often referred to as Cloud Storage).

Concepts of Input and Output

• Data Forms: Data commonly exists as text, point (coordinates/interaction), image, audio, or video.

  • Point Data: This is used specifically to interact with and manipulate objects displayed on a screen.

• The Conversion Process:

  • Input: Input devices and their associated software convert human-readable forms (text, point, image, audio, or video) into digital bits ($0s$ and $1s$) for computer processing and storage.

  • Output: Output devices and software convert processed bits back into forms that humans can understand.

Text Input Devices

• Keyboards: The primary input device for text.

  • Configuration: Typically use the typewriter-style layout known as QWERTY.

  • Function: Used to input characters including alphabetical letters, numbers, and symbols.

  • Connectivity: Can be built into the device or connected via ports, wires, or wireless technology (e.g., Bluetooth).

  • Standard Key Clusters:

    • Standard alphanumeric keys.

    • Numeric keypad (for rapid data entry).

    • Function keys (F1-F12).

    • Directional keys (arrows) and special purpose keys.

Point Input Devices

• Definition: A pointing device moves a pointer (which may appear as a cursor, arrow, or insertion point) on a screen to interact with graphical objects.

• Common Actions: Starting programs, opening files, scrolling/swiping through content, editing documents (copy, cut, paste), and drawing or editing images.

• Types of Pointing Devices:

  • Mouse: Includes traditional mechanical/optical mice and Touch Mice (which respond to swipes for scrolling and taps for clicking).

  • Electronic Pen / Stylus: Used for drawing or writing directly on screens.

  • Touch Enabled Screens: Allow direct interaction with the display using fingers.

  • Other variants: Touchpad (common on laptops), Tracking Ball, Joystick, and Control Wheel.

Visual and Biometric Input

• Scanners: Devices used to convert physical documents into digital images.

  • Flatbed Scanners: Used for photos, sketches, slides, and book pages.

  • Portable Scanners: Designed for capturing documents on the go; data is usually transferred to a computer later.

  • Portable 3D Scanners: Used to capture the three-dimensional digital geometry of a person or an object.

• Biometric Readers: Used to input unique biological data for security and identification. Types include:

  • Fingerprint readers (often built into PC home buttons or mobile device screens/buttons).

  • Retina scanners.

  • Facial feature recognition.

  • Voice recognition.

• Digital Cameras: Capture images and video in digital form.

  • Resolution: Quality is measured in Mega Pixels (MP).

  • Digital Video Cameras: Specifically designed to record moving images as digital data.

Audio Input

• Voice Narrations: Used for recordings like podcasts; primarily captured via a Microphone.

• Instrumental Sound: Sounds from musical instruments, such as MIDI (Musical Instrument Digital Interface) keyboards, which connect directly to a computer's sound card.

Visual Output

• Display Screens and Monitors: Present visual output including text, images, and video.

  • Color Composition: All colors on a display are generated by mixing three primary additive colors: Red, Green, and Blue (RGB).

• Data Projectors: Also called Multimedia Projectors, these cast computer output onto walls or large projection screens.

• 3D Projectors: Capable of showing three-dimensional output.

  • Requires the use of special 3D glasses.

  • Advanced versions can display holograms.

Hardcopy Output (Printers)

• Definition: Printers produce physical output on various surfaces such as paper, cloth, or metallic sheets.

• Quality Metrics:

  • Resolution: Measured in dots per inch (DPI).

    • $300\,DPI$: Standard for general-purpose use.

    • $1200\,DPI$: Standard for high-quality photographs.

    • $2400\,DPI$: Used for professional high-quality marketing materials.

• Speed Metrics:

  • Measured in Pages Per Minute (PPM) or Images Per Minute (IPM).

  • Typical PPM ranges from $10$ to $65\,PPM$.

• Color Printing: Uses the subtractive color model, mixing three basic colors: Cyan, Magenta, and Yellow (CMY). Black ink or toner is usually provided separately as a fourth component (yielding CMYK) because it is used more frequently.

• Printer Technologies:

  • Laser Printers: Use toner (powder) and heat to fuse the image to the paper. They are generally faster and produce higher quality than inkjets.

  • Inkjet Printers: Spray tiny droplets of liquid ink onto the surface. They are typically cheaper than laser printers.

• Printer Variations:

  • Connection Options: USB ports, wired networks (Ethernet), Wi-Fi, or Bluetooth.

  • Personal vs. Network: Personal printers connect to one PC; network printers connect to a whole office and may support Cloud Printing.

  • Multi-Function Devices (MFDs): Single units that can copy, fax, scan, and print.

  • Integrated Printers: Built directly into other devices like digital cameras or smartphones.

  • Large-Format Printers: Used for blueprints, posters, signs, and maps.

  • 3D Printers: Build physical 3D objects by depositing materials (like plastic) in successive layers.

Audio Output

• Speakers: The most common device for voice, music, and audible alerts.

• Headphones and Earbuds: Portable versions of speakers for individual use.

• Screen Readers: Specialized combinations of software and speakers used to provide an audible version of on-screen data for visually impaired individuals.

Questions & Discussion

• The session concludes with an invitation for questions from the audience.