Hard Disk CD-ROM

HiFD™ (High-Capacity

Floppy Disk) drive

Uses a 200 MB HiFD™ disk

Developed by Sony Electronics, Inc.

High-Capacity DisksWhat is a high-capacity disk drive?• A disk drive that uses disks with capacities of 100 MB and

greater

SuperDisk™ drive

Uses a 120 MB or a 250 MB SuperDisk™

Developed by Imation

Zip® drive

Uses a Zip® disk that can store 100 MB or 250 MB of

data

Developed by Iomega Corporation

built in Zip® drive

Hard DisksWhat 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

Hard disk installed in system unit

Step 4: The head actuator positions the read/write head arms over the correct location on the platters to read or write data

Step 4

Step 2: A small motor spins the platters while the computer is running

Step 2

Step 3: When software requests a disk access, the read/write heads determine the current or new location of the data

Step 3

Step 1: The circuit board controls the movement of the head activator and a small motor

Step 1

Hard DisksHow does a hard disk work?

Hard DisksWhat 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

trackcylinder

Hard DisksHow 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

Hard disk

Approximately 5 to 11

milliseconds

Floppy disk

84 milliseconds or approximately ½ a

second

Hard DisksWhat 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

• instructions, and information to improve data reliability

drive C

Designation for first partition or for a single

partition on the hard disk

drive D

Designation for second partition on the hard

disk

Hard Disks

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

What utilities maintain a hard disk drive?

Compact DiscsWhat 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 compactdisc drive

• Also called an optical disc

• Available in a variety of formats

CD-RO

M

CD-RCD-RW

DVD-ROM

Step 3: Reflected light is deflected to a light-sensing diode, which sends digital signals of 1 to the computer. Absence of reflected light is read as a digital signal of 0.

Step 1: A laser diode shines a light beam toward the compact disc.

Step 2: If light strikes a pit, it scatters. If light strikes land, it is reflected back toward the laser diode.

Compact disc label

Compact disc label

lens lens

prism prism

laser diode

laser diode

Step 1Compact disc

label

lens lens

prism prism

laser diode

laser diode

• 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

Compact DiscsHow does a laser read data on a compact disc?

Step 2Compact disc

label

lens lens

prism prism

laser diode

laser diode

pit land

Step 3Compact disc

label

lens lens

prism prism

laser diode

laser diode

Light-sensing

diode

Light-sensing

diode

0 1

pit land

CD-ROMsWhat 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

40X 40 X 150 KB per second =

6,000 KB per second or 6 MB per second

CD-ROMsWhat 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)

75X 75 X 150 KB per second =

12,250 KB per second or 12.25 MB per second

range of current rates

CD-R and CD-RWWhat 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

The CD-R drive can read and write both audio CDs and standard CD-ROMs

You cannot erase the disc’s contents

Most CD-ROM drives can read a CD-R

CD-R and CD-RWWhat 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 Discs can be read only

by multiread CD-ROM drives

• Drives that can read audio CDs, data CDs, CD-Rs, and CD-RWs

• Most recent CD-ROM drives are multiread

DVD-ROMsWhat 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

DVD-ROMsWhat are other various DVD formats?

Digital motion picture DVD

Used to play a movie on your television set or view on the

computer

DVD-R (DVD-recordable)A recordable DVD that you can write on once and read

from many times

DVD+RW

A competing technology to DVD-RAM

DVD-RAMA rewritable DVD that allows you to erase and record on

the disc multiple times

TapesWhat 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

TapesWhere 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

Miniature Mobile Storage MediaWhat is miniature mobile storage media?• Handheld

devices use miniature mobile storage media to augment internal storage

Storage CapacityDevice Name Type, Use

Clik! Disk

CompactFlash

Microdrive

SmartMedia

40 MB

2 to 256 MB

1 GB

2 to 128 MB

Cartridge

Digital cameras, notebook computers

Memory Card

Digital cameras, handheld computers, notebook computers, printers, cellular telephones

Memory card

Digital cameras, handheld computers, music players, video cameras

Memory Card

Digital cameras, handheld computers, photo printers, cellular telephones

Typical I/O Data Rates