Chapter 7 - Storage

Memory Versus Storage

What is storage?

°    The media on which data, instructions, and information are kept, as well as the devices that record and retrieve these items

What is memory?

°    A temporary holding place for data and instructions

°    Consists of one or more chips on the motherboard

°    Sometimes called primary storage

How does storage differ from memory?

°     Storage also called secondary storage, auxiliary storage, permanent storage, or mass storage

°     Storage holds items such as data, instructions, and information for future use

°     Storage is nonvolatile

How does volatility compare?

What is a storage medium and a storage device?

What is reading and writing?

Reading

Process of transferring data, instructions, and information from a storage medium into memory

 Serves as a source of input

What is access time?

°    The amount of time it takes the device to locate an item on a disk

°    Defines the speed of a disk storage device

What is capacity?

°    The number of bytes (characters) a storage medium can hold

°    Manufacturers use many terms to define the capacity of storage media

 

Technology Trailblazer

Al Shugart

°     Joined IBM as a customer engineer in 1951

°     Supervised a team in 1967 responsible for developing a removable, portable data storage device

°     Founded Shugart Associates in 1973 and Seagate Technology in 1979

 

Floppy Disks

What is a floppy disk?

°    A portable, inexpensive storage medium

°    Consists of a thin, circular, flexible plastic disk with a magnetic coating

°    Enclosed in a square-shaped plastic shell

°    Today’s standard disk is 3.5” wide

What are the parts of a floppy disk?

°    A thin circular flexible film is enclosed between two liners

°    A piece of metal called a shutter covers an opening to the recording surface

What is a floppy disk drive (FDD)?

°    A device that can read from and write on a floppy disk

°    Most personal computers have a floppy disk drive, in which you insert and remove a floppy disk

How are floppy disk drives designated?

How does a floppy disk store data?

°    A type of magnetic media

°    Uses magnetic patterns to store items such as data, instructions, and information on a disk’s surface

°    Able to access (read) data from and place (write) data on a magnetic disk any number of times

°    The read/write head in the
floppy disk drive is the
mechanism that actually
reads items from or writes
items on the floppy disk

How does a floppy disk drive work?

What is density?

°    The number of bits in an area on a storage medium

°    A floppy disk drive must support that floppy disk’s density

°    Most floppy disks today are high density (HD) with a capacity of 1.44 MB

What are tracks and sectors?

°     Track: a narrow recording band that forms a full circle on the surface of the disk

°     Pie shaped sections break the tracks into small arcs  called sectors

°     A sector can store up to 512 bytes of data

°     A typical floppy disk stores data on both sides of the disk

What is a cluster?

°    The smallest unit of disk space that stores data

°    Also called an allocation unit

°    2 to 8 sectors depending on the operating system

°    Each cluster holds data from only one file

°    One file can span many clusters

What is formatting?

°    The process of preparing a disk for reading and writing

°    Formatting marks bad sectors as unusable

How do you care for a floppy?

°    A floppy disk can last at least seven years

°    Proper care helps to maximize a disk’s life

What is a write-protect notch?

°    A small opening with a cover that you slide up or down

°    Protects floppy disks from accidentally being erased

 

High-Capacity Disks

What is a high-capacity disk drive?

°    A disk drive that uses disks with capacities of 100 MB and greater

What is a backup?

°    A duplicate  of a file, program, or disk that you can use if the original is lost damaged, or destroyed

°    High-capacity disks are often used to
back up
important
data and
information

 

Hard Disks

What a hard disk?

°    Consists of several inflexible, circular platters that store items electronically

°    Also called a hard disk drive or a fixed disk

°    A platter is coated with a material that allows items to be recorded magnetically on its surface

°    The components of a hard disk are enclosed in an airtight, sealed case to protect them

How does a hard disk work?

What is a cylinder?

°    The location of a single track through all platters

°    A single movement of the read/write head arms can read all the platters of data

What is a head crash?

°    Occurs when a read/write head touches the surface of a platter

°    The platters of the hard disk rotate at a high rate of speed while the computer is running

°    The spinning creates a cushion of air that floats the read/write head above the platter

How does access time compare for a hard disk and a floppy disk?

°    A hard disk’s access time is significantly faster than a floppy disk

•    The hard disk spins much faster than a floppy disk

•    A hard disk spins constantly, while a floppy disk starts spinning only when it receives a read or write command

What is a disk cache?

°    A portion of memory that the processor uses to store frequently accessed items

What is a partition?

°    You can divide a formatted hard disk into separate areas called partitions

°    Done by issuing a special operating system command

°    Each partition functions as if it were a separate hard disk drive

What is a disk controller?

°    A special purpose chip and associated electronic circuits that control the transfer of data, instructions, and information from a disk to the rest of the computer

°    Sometimes called an interface

°    A hard disk controller (HDC) is the interface for a hard disk

°    May be part of the disk drive or a separate card inside the system unit

What is a removable hard disk?

°    A disk drive in which a plastic or metal case surrounds the hard disk so you can remove it from the drive

°    A popular, reasonably priced, removable hard disk is the Jaz^® disk by Iomega

 

Company on the Cutting Edge

Kingston Technology

°    The world’s leading independent manufacturer of memory
products of computers,
servers, digital cameras, and
other electronic devices

°    Founded by John Tu and
David Sun in 1987

°    Markets more than 2,000
products

°    Designated as one of the 100 Best Companies to Work for in the United States by Fortune magazine

 

Hard Disks

What is RAID?

°    Redundant array of independent disks

°    A type of hard disk system that connects several smaller disks into a single unit that acts like a single large hard disk

°    More reliable than a traditional disk system but quite expensive

How does RAID work?

°     RAID duplicates data, instructions, and information to improve data reliability

What utilities
maintain a hard
disk drive?

°    Windows provides many maintenance and monitoring utilities for a hard disk on the System Tools submenu

What is an Internet hard drive?

°    A service on the Web that provides storage to computer users

°    Sometimes called online storage

°    Many offer storage free of charge

°    Revenues come from advertisers

What are advantages of an Internet hard drive?

 

Compact Discs

What is a compact disc (CD)?

°    A flat, round, portable, metal storage medium that usually is 4.75 inches in diameter and less than one-twentieth of an inch thick

°    Most personal computers today include some
type of compact
disc drive

°    Also called an
optical disc

°    Available in a
variety of formats

How do you use a compact disc?

°     CD drives can read compact discs, including audio discs

°     Most CD drives include a volume control button and a headphone jack

°     The drive designation of a CD drive usually follows alphabetically after that of the hard disk

How does a laser read data on a compact disc?

°     Items are stored using microscopic pits (indentations) and land (flat areas) that are in the middle layer of the disk

°     A laser light reads items from the compact disc

How is data stored on a compact disc?

°    A compact disc typically stores items in a single track

°    It spirals from the center of the disc to the edge of the disc

°    The track is divided into evenly sized sectors in which items are stored

What is a jewel box?

°    A protective case for a compact disc

°    Place a compact disc in a jewel box to protect data

How should you care for a compact disc?

 

CD-ROMs

What is a CD-ROM?

°    A silver-colored compact disc that uses the same laser technology as audio CDs for recording music

°    Can contain text, graphics, audio, and video

°    The manufacturer writes, or records, the contents of standard CD-ROMs

°    You cannot erase or modify the contents

°    A CD-ROM drive or CD-ROM player is used to read items on a CD-ROM

What is the storage capacity of a CD-ROM?

°    A typical CD-ROM holds about 650 MB of data, instructions, and information

°    Manufactures use CD-ROMs to store and distribute today’s
multimedia
and other
complex
software

What is the data transfer rate of a CD-ROM drive?

°    The time it takes a drive to transmit data, instructions, and information from the drive to another device

°    Slower CD-ROM drives produce choppy images or sound

°    Drive speed measured relative to original CD-ROM drives (150 KB per second)

What is a PhotoCD?

°    A compact disc that contains digital photographic images saved in the PhotoCD format

°    Based on a file format developed by Eastman Kodak

°    Used by commercial and
professional users

What is a Picture CD?

°    A single-session disc offered by Kodak

°    Stores digital versions of photographs for consumers

°    Single-session means all items are written to the disc at one time

°    Film developers create the images on the disc from photographic negatives at the time a roll of film is developed

 

CD-R and CD-RW

What is a CD-R (compact disc-recordable)?

°    A multisession compact disc onto which you can record your own items such as text, graphics, and audio

°    You write on the CD-R using a CD recorder or a CD-R drive and special software

What is a CD-RW (compact disc-rewritable)?

°    An erasable disc you can write on multiple times

°    You must have CD-RW software
and a CD-RW drive

 

 

How is an audio
CD created?

 

DVD-ROMs

What is a DVD-ROM (digital video disc-ROM)?

°    An extremely high capacity compact disc capable of storing from 4.7 GB to 17 GB

°    You must have a DVD-ROM drive or DVD player to read a DVD-ROM

°    Looks just like a CD-ROM but data, instructions, and information is stored in a slightly different manner to achieve a higher storage capacity

How does a DVD-ROM store data?

°    Three storage techniques used to store DVD-ROM data

•     Pits are packed closer together to make the disc more dense

•     Two layers of pits are used, where the lower layer is semitransparent so the laser can read through it to the upper layer

•     Some are double-sided, which means you can remove the DVD-ROM and turn it over to read the other side

What are other various DVD formats?

 

Technology Trailblazer

Mark Dean

°     Designs microprocessors, improvements in architecture, and hardware innovations for IBM

°     First African-American to receive an IBM Fellowship, the company’s highest technical ranking

°     Inducted into the National Inventor's Hall of Fame

 

Company on the Cutting Edge

EMC2

°    A provider pf storage systems for some of the  world’s largest corporations

°    Founded in 1979 by Richard Egan and Roger Marino to fill a demand for add-on memory boards in the minicomputer market

 

Tapes

What is tape?

°     A magnetically coated ribbon of plastic capable of storing large amounts of data and information at a low cost

°     A tape drive reads from and writes data and information on a tape

°     Older computers used reel-to-reel tape drives

°     A tape cartridge is a small, rectangular, plastic housing for tape used in
today’s tape
drives

Where is tape used?

°    Used by business and home users to backup personal computer hard disks

°    Both external and internal tape units for personal computers

°    Larger computers use tape cartridges mounted in a separate cabinet called a tape library

°    Three common types of tape drives

What is sequential access versus direct access?

 

Enterprise Storage Systems

What is an enterprise storage system?

°     A strategy that focuses on the availability, protection , organization, and backup of storage in a company

°     Goal is to consolidate storage so operations run as efficiently as possible

What storage techniques are used in an enterprise system?

How do organizations handle storage?

 

PC Cards

What is a PC Card?

°    A thin, credit card-sized device

°    Fits into a PC Card slot on a notebook other personal computer

°    Different types and sizes add storage, additional memory, communications, and sound capabilities to a computer

What are the uses of PC Cards?

°    Three types of PC Card

°    Advantage of a PC Card for storage is portability between systems

 

Miniature Mobile Storage Media

What is miniature mobile storage media?

°    Handheld devices use miniature mobile storage media to augment internal storage

How is miniature storage media used?

°    Handheld devices, such as players and wallets, read or display the contents of miniature storage media such as memory cards

What is a smart card?

°    Stores data on a thin microprocessor embedded in the card

°    Similar in size to a credit card

°    Read smart card with a specialized card reader

°    Information on the smart card can be read and updated

What are the types of smart cards?

°    Intelligent smart card contains a processor and has input, process, output, and storage capabilities

°    Memory card has only storage capabilities

What is electronic money?

°    A means of paying for goods and services over the Internet

°    Also called digital cash

 

Microfilm and Microfiche

What are microfilm and microfiche?

°    Store microscopic images of documents on roll or sheet film

°    Images recorded onto film using a computer output microfilm (COM) recorder

°    Images can only be read with a microfilm or microfiche reader

How do life expectancies of various media compare?

°    Microfilm and microfiche are inexpensive and have the longest life of any storage medium

 

Summary

What are suggested storage devices for computer users?

 

Summary of Storage

°    Memory versus storage

°    Floppy disks

°    High-capacity disks

°    Hard disks

°    Compact discs

°    CD-ROMs

°    CD-R and CD-RW

°    DVD-ROMs

°    Tapes

°    Enterprise storage systems

°    PC Cards

°    Miniature mobile storage media

°    Microfilm and microfiche

Chapter 7 Complete