1. Hard Disk CD-ROM

2. High-Capacity Disks What 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
HiFD™ (High-Capacity Floppy Disk) drive
Uses a 200 MB HiFD™ disk
Developed by Sony Electronics, Inc.
Zip® drive
Uses a Zip® disk that can store 100 MB or 250 MB of data
Developed by Iomega Corporation
built in Zip® drive

3. Hard disk installed in system unit
Hard Disks
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
What a hard disk?
Hard disk installed in system unit
Introduction Computer Hardware Jess 2006

4. Hard Disks How does a hard disk work?
Step 1: The circuit board controls the movement of the head activator and a small motor
Step 1
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 4: The head actuator positions the read/write head arms over the correct location on the platters to read or write data
Step 4

5. Hard Disks What is a cylinder?
track
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

6. Hard Disks
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
Hard disk
Approximately 5 to 11 milliseconds
Floppy disk
84 milliseconds or approximately ½ a second

7. Designation for second partition on the hard disk
Hard Disks
drive C
Designation for first partition or for a single partition on the hard disk
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
instructions, and information to improve data reliability
drive D
Designation for second partition on the hard disk

8. Hard Disks
What utilities maintain a hard disk drive?
Windows provides many maintenance and monitoring utilities for a hard disk on the System Tools submenu

9. Compact Discs CD-ROM CD-RW CD-R DVD-ROM 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
CD-RW
CD-R
DVD-ROM

10. Compact Discs 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
Step 2
Compact disc label
lens
prism
laser diode
pit
land
Step 3
Compact disc label
lens
prism
laser diode
Light-sensing diode 1
pit
land
Step 1
Compact disc label
lens
prism
laser diode
Compact disc label
lens
prism
laser diode
Compact disc label
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.

11. CD-ROMs 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

12. 40X 40 X 150 KB per second = 6,000 KB per second or 6 MB per second
CD-ROMs
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)
40X 40 X 150 KB per second = 6,000 KB per second or 6 MB per second
range of current rates
75X 75 X 150 KB per second = 12,250 KB per second or MB per second

13. 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
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

14. CD-R and CD-RW 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
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

15. 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

16. DVD-ROMs What are other various DVD formats?
Digital motion picture DVD
Used to play a movie on your television set or view on the computer
DVD-RAM
A rewritable DVD that allows you to erase and record on the disc multiple times
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

17. 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

18. Tapes 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

19. Miniature Mobile Storage Media
What is miniature mobile storage media?
Handheld devices use miniature mobile storage media to augment internal storage
Storage Capacity
Device Name
Type, Use
Clik! Disk
40 MB
Cartridge
Digital cameras, notebook computers
CompactFlash
2 to 256 MB
Memory Card
Digital cameras, handheld computers, notebook computers, printers, cellular telephones
Microdrive
1 GB
Memory card
Digital cameras, handheld computers, music players, video cameras
SmartMedia
2 to 128 MB
Memory Card
Digital cameras, handheld computers, photo printers, cellular telephones

20. Typical I/O Data Rates