Digital Storage and Memory Notes

Computing Components

Hardware for Home and Work

  • Includes input and output devices.

Digital Storage

  • Preserving digital content is a key aspect.

Digital Storage: Preserving Your Content

Storage and Memory Uses

  • Computers use both storage and memory to access and save data.
  • Memory: Electronic components storing instructions, data needed by instructions, and results of processing.
  • Storage: Long-term, permanent access to data.
  • Analogy: Storage is like a file cabinet for digital content.
Volatile vs. Non-Volatile Memory
  • Storage medium: Nonvolatile.
  • Most memory (RAM): Volatile, holding data temporarily.
  • Volatile memory: Stores data only when the computer is on; erases data when switched off.
  • Non-volatile memory: Retains data even after the system is shut off.
Storage Medium
  • Also called secondary storage.
  • Location where a computer keeps data, information, programs, and applications.
  • Examples: Digital storage (cloud), hard disks, solid-state drives (internal/external), memory cards, USB flash drives, optical discs, tags.
  • Cloud storage: Keeps information on servers on the Internet.
  • Users store various data types on storage media on computers, mobile devices, or cloud storage.
Storage Devices: The Hardware
  • Hardware that records and/or retrieves items to and from storage media.
Writing and Reading
  • Writing: Transferring data, instructions, and information from memory to a storage medium.
  • Reading: Transferring items from a storage medium into memory.
Capacity of Storage
  • The number of bytes a storage medium can hold.
  • Kilobyte (KB): Approximately 1 thousand bytes.
  • Megabyte (MB): Approximately 1 million bytes.
  • Gigabyte (GB): Approximately 1 billion bytes.
  • Terabyte (TB): Approximately 1 trillion bytes.
  • Petabyte (PB): Approximately 1 quadrillion bytes.
  • Exabyte (EB): Approximately 1 quintillion bytes.
  • Zettabyte (ZB): Approximately 1 sextillion bytes.
  • Yottabyte (YB): Approximately 1 septillion bytes.
Speed of Storage Devices and Memory
  • Defined by access time.
    • Measures the time it takes for a storage device to locate an item.
    • Measures the time required to deliver an item from memory to the processor.
  • Transfer rate: Speed with which data transfers to and from a device, stated in KBps, MBps, and GBps.

Storage Hardware

Hard Drives

  • Most common storage medium: Internal hard drive.
  • Can store data magnetically or using solid-state storage.
  • Files stored on the internal hard drive cannot be accessed on other devices.
  • Magnetic hard disk drives (HDDs) have greater storage capacity and are less expensive than solid-state drives (SSDs).
  • The term “hard drive” refers collectively to hard disks and SSDs.
Hard Disk Drives (HDDs)
  • Storage device containing one or more inflexible, circular platters using magnetic particles to store data.
  • Desktops and laptops contain at least one hard disk.
  • Storage capacity is determined by:
    • Number of platters.
    • Composition of the magnetic coating on platters.
    • Use of longitudinal or perpendicular recording.
    • Density.
Characteristics of a Hard Disk
  • Tracks
  • Sectors
  • Platters
  • Form factor
  • Read/write head
  • Revolutions per minute
Platter Composition and Recording Methods
  • Platter: Made of aluminum, glass, or ceramic with a thin alloy coating for magnetic recording.
  • Longitudinal recording: Aligns magnetic particles horizontally.
  • Perpendicular recording: Aligns magnetic particles vertically.
  • Density: Number of bits in an area on a storage medium; higher density means more storage capacity.
  • Perpendicular recording stores up to three times the storage compared to longitudinal recording.
Formatting
  • The process of dividing the disk into tracks and sectors.
  • Track: Concentric circles on a magnetic hard disk platter.
  • Sector: Wedge-shaped section that breaks tracks into small arcs.
  • Several sectors form a cluster.
Read/Write Head
  • A typical hard disk has multiple platters, each with two read/write heads (one for each side).
  • Read/write head: Mechanism that reads and writes items to the drive.
  • A hard disk head actuator connects to arms that move the read/write heads to the correct location.
Platter Rotation
  • While the computer is running, the platters rotate at a high speed, allowing quick access to tracks and sectors.
  • Platters may slow down after a specified time to save power.
  • Spinning creates a cushion of air between the platter and the read/write head, preventing direct contact.
External Hard Drives
  • Separate, free-standing storage device connecting via USB or other port.
  • Sizes and storage capacities vary.
  • Entire drive enclosed in an airtight, sealed case.

Solid-State Drives (SSDs)

  • Flash memory storage device.
  • Flash memory: Nonvolatile memory that can be erased electronically and rewritten.
  • Flash memory chips are solid-state media, containing no moving parts.

Portable Flash Memory Storage

Memory Cards
  • Removable flash memory storage device.
  • Used to transport digital data between mobile devices and computers.
  • A slot on a computer accepts multiple card types.
USB Flash Drives
  • Removable storage device plugging into a USB port.
  • Used for transporting folders and files to other computers.
  • Storage capacities vary.

Optical Media

  • Includes CDs, DVDs, and Blu-ray discs (BDs), but their use is declining.
  • Optical disc: Flat, round, portable disc made of metal, plastic, and lacquer, written and read by a laser.
Optical Disc Formats
  • CD:
    • CD-ROM (read-only)
    • CD-R (recordable)
    • CD-RW (rewritable)
    • Used for audio and photos.
  • DVD:
    • DVD-ROM (read-only)
    • DVD-R, DVD+R (recordable)
    • DVD-RW, DVD+RW, DVD+RAM (rewritable)
    • Used for video.
  • Blu-ray:
    • Higher capacity than DVD.
    • Used for video.

Cloud Storage

Cloud Computing Basics

  • Chosen for accessibility, cost-saving, space-saving, and scalability.
  • Consists of a front end and a back end, connected through a network.
    • Front end: Hardware and software used to access the cloud.
    • Back end: Servers and storage devices that manage resources.

Cloud Computing Applications

  • Allows companies to outsource elements of their IT infrastructure to third-party providers.
  • Cloud storage providers enable file synchronization, document writing, backups, project sharing, media streaming, etc.

Cloud Service Models

  • SaaS (Software as a Service).
  • IaaS (Infrastructure as a Service).
  • STaaS (Storage as a Service).
  • DaaS (Data as a Service).
  • PaaS (Platform as a Service).
Additional Cloud Services
  • Synchronize files.
  • Write documents.
  • Backup files.
  • Stream media.

Cloud Storage Options

  • Google Drive and Microsoft OneDrive offer cloud-based apps for file creation, editing, and sharing.
  • Other options like Box are primarily storage locations without corresponding apps.
  • Files are protected by security measures such as passwords, identification, and encryption; backups on other servers ensure availability.
  • Advantage: Eliminates the need to purchase and maintain servers.

Considerations for Cloud Storage Providers

  • Select providers with sufficient bandwidth for large file transfers (photos, songs, videos).
  • Consider:
    • Amount of free storage offered.
    • Cost to purchase additional storage.
    • Maximum file size allowed for upload.
  • Review privacy policy and terms of agreement.

Guidelines for Selecting a Cloud Storage Provider

  • Verify the company’s reputation and longevity.
  • Choose a provider that encrypts files.
  • Ensure compatibility with computers and mobile devices.
  • Compare pricing and choose a competitive plan.
  • Verify support for desired file types.
  • Choose a provider that allows file sharing.
  • Consider a provider with a mobile app for access.

Secure IT: Secure Your Data on the Cloud

Digital Currency and Payment Methods

  • Cryptocurrency: Digital currency for transferring money without government backing.
  • Payment apps (e.g., Venmo): Transfer money between credit cards/bank accounts and other users.
  • Digital wallet (e.g., ApplePay): App connected to a payment card or financial account.

Steps to Protect Cloud-Based Data

  • Choose cloud providers carefully.
  • Read user agreements.
  • Set advanced privacy settings.
  • Use strong passwords and two-factor authentication.
  • Encrypt sensitive data before storing it.

Enterprise and Other Storage Options

Enterprise Hardware

  • Designed for large organizations to manage data with devices intended for heavy use and maximum availability.
  • Hardware should be accessible 24/7/365.
  • Includes levels of redundancy: if one component fails, another takes over.
  • Enterprise storage centers/data centers: Secure locations with large computers acting as servers.

Storage Management

  • Organizations may manage storage in-house or outsource to a provider.
  • RAID (Redundant Array of Independent Disks): Group of integrated hard drives to improve data reliability.
  • RAID may duplicate data.
RAID Levels
  • Level 1 (Mirroring): Writes data on two drives simultaneously to duplicate data.
  • Other levels use striping: Splits data across multiple drives.
  • Striping improves drive access times.

Network Attached Storage (NAS)

  • Server placed on a network to provide storage to users and devices.
  • NAS has its own IP address, typically no keyboard/display, and contains at least one hard drive, often in a RAID configuration.
  • Administrators can quickly add storage by connecting a NAS server.

Storage Area Network (SAN)

  • High-speed network providing storage to attached servers.
  • SAN includes only storage devices.
  • High-speed fiber-optic cables connect other networks and servers.
  • SAN can connect to networks and servers miles away.

Other Types of Storage

  • Tape, magnetic stripe cards, smart cards, RFID tags, and NFC chips/tags.
  • Tape: Magnetically coated plastic ribbon for large data storage at a low cost.
  • Magnetic stripe card: Credit, entertainment, or bank card with a stripe containing identification information.
  • Smart card: Stores data on an integrated circuit embedded in the card; contact and contactless types exist.
RFID (Radio-Frequency Identification) Tags
  • Consists of an antenna and memory chip.
  • Transmits stored information via radio waves.
  • RFID reader captures radio signals.
  • Tags can be active or passive.
NFC (Near Field Communication)
  • Technology based on RFID using close-range radio signals.
  • Used for data transmission between two NFC-enabled devices or an NFC-enabled device and an NFC tag.
  • NFC-enabled devices contain an NFC chip.
  • NFC tags are self-adhesive.

NFC Tag Uses

  • Include using a mobile device to pay for goods or services, displaying a web page, making a phone call, sending a text message, or exchanging contact information.

How Memory Relates to Storage

Memory Components and Storage

  • Memory consists of chips on the motherboard.
  • Stores:
    • The operating system and other programs.
    • Applications that carry out tasks.
    • Data being processed by applications.

Bytes and Addresses

  • Byte: Basic storage unit in memory.
  • Instructions and data are transferred to memory as bytes.
  • Each byte resides in a memory location with a unique address.
  • The computer references addresses to access data.

Memory Capacity

  • Affects device operation speed.
  • RAM (Random Access Memory): Most common type of volatile memory.
  • Examples of nonvolatile memory: ROM, flash memory, and CMOS.
  • RAM is also called main memory.
  • Can accommodate multiple programs simultaneously.
  • Saving: Copying data from RAM to a storage device or the cloud.
  • Cache: Temporary storage area that speeds up processing by storing frequently used instructions and data.

Program Instructions Transfer in and Out of RAM (Example Steps)

  1. Operating system files are loaded into RAM from the hard drive; the user interface is displayed.
  2. A browser's instructions are loaded into RAM; the browser window appears.
  3. A paint application's instructions are loaded into RAM alongside the browser; the paint application window appears.
  4. When an application is exited, its instructions are removed from RAM.

ROM (Read-Only Memory)

  • Refers to memory chips storing permanent data and instructions.
  • Data cannot be modified.
  • Manufacturers record data on firmware chips during manufacturing.
  • Contains permanently written data, such as start-up instructions.

Flash Memory

  • Non-volatile memory that can be erased electronically and rewritten.
  • Used for start-up instructions in most computers.
  • Stores data and programs on mobile devices, such as smartphones, and peripheral devices, such as printers and digital cameras.

CMOS (Complementary Metal-Oxide Semiconductor)

  • Used in RAM, flash memory, and other memory chips.
  • Provides high speeds and consumes little power.
  • Uses battery power to retain information even when the computer is off.
  • Battery-backed CMOS memory chips often store a computer’s startup information.

Ethics and Issues: Internet of Things and Privacy

IoT and Data Collection

  • Smart electric meters, wearable technology, and vehicle black boxes submit data.
  • A thermostat allows remote temperature adjustments.
  • Medicine bottles with wireless chips send reminders.

IoT Applications

  • Smart trash cans monitor trash levels and send notifications.
  • Wearable technology tracks pulse and heart rate; accepts calls and displays notifications.
  • Retailers use beacons to send personalized offers to customers through payment apps.

Privacy and Security Concerns

  • Devices could have default settings that prevent data sharing without consent.
  • Companies must ensure sensitive data is kept secure.
  • Technology experts believe the benefits of this technology outweigh the potential risks.