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Living in a Digital World

Discovering � Computers 2011

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Introduction

  • An essential feature of every computer is the ability to save, or store, information.
  • Before data can be processed or a program can be run, it must be in RAM. For this reason, RAM is sometimes referred to as primary storage.
  • Unfortunately, most RAM provides only temporary or volatile storage. That is, it loses all of its contents as soon as the computer is turned off.
  • This volatility results in a need for more permanent or nonvolatile storage for data and programs.
  • Secondary storage provides permanent or nonvolatile storage.
  • Using secondary storage devices such as a hard-disk drive, data and programs can be retained after the computer has been shut off.

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Storage

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Storage holds data, instructions, and information for future use

A storage medium is the physical material on which a computer keeps data, instructions, and information

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Storage

Pages 352 – 353

Figure 7-1

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Storage

  • Capacity is the number of bytes a storage medium can hold

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Figure 7-2

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Storage

  • A storage device is the computer hardware that records and/or retrieves items to and from storage media

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Reading is the process of transferring items from a storage medium into memory

Writing is the process of transferring items from memory to a storage medium

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Storage

  • Access time measures:
    • The amount of time it takes a storage device to locate an item on a storage medium
    • The time required to deliver an item from memory to the processor

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Hard Disks

  • A hard disk contains one or more inflexible, circular platters that use magnetic particles to store data, instructions, and information

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Figure 7-5

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Cont.…

  • Hard disks save files by altering the magnetic charges of the disk’s surface to represent 1s and 0s.� Hard disks retrieve data and programs by reading these charges from the magnetic disk.

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Hard Disks

  • The hard disk arms move the read/write head, which reads items and writes items in the drive.

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Figure 7-10

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Hard Disks structure

  • Hard disks use platters that are stacked one on top of another.
  • Hard disks store and organize files using tracks, sectors, and cylinders.
  • Tracks are rings of concentric circles on the platter. Each track is divided into invisible wedge-shaped sections called sectors.
  • A cylinder runs through each track of a stack of platters.

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Figure 7-8

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Hard Disks structure

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Hard Disks

  • A head crash occurs when a read/write head touches the surface of a platter
  • Always keep a backup of your hard disk

Pages 358 – 359

Figure 7-11

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Hard Disks

  • Formatting is the process of dividing the disk into tracks and sectors so that the operating system can store and locate data and information on the disk

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Hard Disks

Pages 360 – 361

Figures 7-14 – 7-15

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An external hard disk is a separate free-standing hard disk that connects to your computer with a cable or wirelessly

Internal hard disk is located inside the system unit.

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Hard Disks

Disk controller consists of a special-purpose chip and electronic circuits that control the transfer of data, instructions, and information from a disk to and from the system bus and other components of the computer

Pages 361 - 362

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SATA

EIDE

SCSI

SAS

Click to view Web Link,�click Chapter 7, Click Web �Link from left navigation,

then click eSATA �below Chapter 7

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Hard Disks

  • RAID (redundant array of independent disks) is a group of two or more integrated hard disks
  • A network attached storage (NAS) device is a server connected to a network with the sole purpose of providing storage

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Figure 7-13

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Click to view Web Link,�click Chapter 7, Click Web �Link from left navigation,

then click Network Attached Storage below Chapter 7

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Solid-state storage(SDD)

  • Unlike hard disks, which rotate and have read/write heads that move in and out, solid-state storage devices have no moving parts.
  • SSDs are faster and more durable than hard disks. SSDs also require less power, which can lead to increased battery life for laptops and mobile devices.
  • SSDs are more expensive and generally have a lower capacity than hard disks.

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SSD

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Flash Memory Storage

  • A memory card is a removable flash memory device that you insert and remove from a slot in a computer, mobile device, or card reader/writer

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CompactFlash (CF)

Secure Digital (SD)

Secure Digital High Capacity (SDHC)

microSD

microSDHC

xD Picture Card

Memory Stick

Memory Stick Micro (M2)

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Flash Memory Storage

Pages 364 – 365

Figures 7-18 – 7-19

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Click to view Web Link,�click Chapter 7, Click Web �Link from left navigation,

then click SDHC Cards

below Chapter 7

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Flash Memory Storage

  • USB drives, or flash drives
  • These drives conveniently connect directly to a computer’s USB port to transfer files and can have capacities ranging from 1 GB to 1TP
  • USB drives have become a very popular option for transporting data and information between computers, specialty devices, and the Internet

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Cloud Storage

  • Cloud storage is an Internet service that provides storage to computer users

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Figure 7-23

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Cloud Storage

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Figure 7-24

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Cloud Storage

  • Users subscribe to cloud storage for a variety of reasons:

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Access files from any computer

Store large files instantaneously

Allow others to access their files

View time-critical data and images immediately

Store offsite backups

Provide data center functions

Click to view Web Link,�click Chapter 7, Click Web �Link from left navigation,

then click Cloud Storage

below Chapter 7

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Optical Discs

  • An optical disc consists of a flat, round, portable disc made of metal, plastic, and lacquer that is written and read by a laser
  • Typically store software, data, digital photos, movies, and music.

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Optical disc types

  • The most widely used optical discs are CD, DVD, and Blu-ray discs.

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Optical disc types

  • Compact discs (CDs) were the first widely available optical format for PC users.
  • Typically, CD drives store 700 MB (megabytes) of storage. Optical discs that store music are often CD.
  • Digital versatile discs (DVDs) are the standard optical discs in PCs. DVDs are very similar to CDs except that typical DVD discs can store 4.7 GB

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Optical disc types

  • Blu-ray discs (BDs) are the newest form of optical storage designed to store high-definition video, which uses the HD 720 and HD 1080 resolution.

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Other Types of Storage

  • Tape is a magnetically coated ribbon of plastic capable of storing large amounts of data and information
  • A tape drive reads and writes data and information on a tape

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Figure 7-35

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Other Types of Storage

  • A magnetic stripe card contains a magnetic stripe that stores information
  • A smart card stores data on a thin microprocessor embedded in the card

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Figure 7-36

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Click to view Web Link,�click Chapter 7, Click Web �Link from left navigation,

then click Smart Cards

below Chapter 7

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Other Types of Storage

  • Enterprise storage stores huge volumes of data and information for large businesses
    • Uses special hardware for heavy use, maximum availability, and maximum efficiency

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Figure 7-39

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Click to view Web Link,�click Chapter 7, Click Web �Link from left navigation,

then click Enterprise Storage

below Chapter 7

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Summary

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Various storage media and storage devices

Internal hard disks, external and removable hard disks, solid state drives, memory cards, USB flash drives, ExpressCard modules, cloud storage, CDs, DVDs, and Blu-ray Discs, tape, smart cards, and microfilm and microfiche