1. Chapter 2.6 Storage

2. What is storage?
The media on which data, instructions, and information are kept, as well as the devices that record and retrieve these items

3. What is memory? A temporary holding place for data and instructions
Consists of one or more chips on the motherboard
Sometimes called primary storage
Nonvolatile memory
Does not lose its contents when power is removed from the computer
Volatile memory
Loses its contents when the computer’s power is turned off
Most memory is volatile

4. 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
When you want to work with a file, you remove it from storage and place it in memory
When you are finished with the file, you remove it from memory and return it to storage

5. How does volatility compare?
State of Computer ON
OFF
Screen Display Volatile
Contents of Storage Nonvolatile
Contents of Memory (most RAM) Volatile
C6578 print cartridge $30.25 per cartridge 2 cartridges $60.50 total due
Contents of storage retained when power is off
Screen display and contents of most RAM (memory) erased when power is off

6. What is a storage medium and a storage device?
The computer hardware that records and retrieves items to and from a storage medium
storage medium
The physical material on which a computer keeps data, instructions, and information

7. What is reading and writing?
Process of transferring data, instructions, and information from a storage medium into memory
Serves as a source of input
Writing
Process of transferring items from memory to a storage medium
Serves as a source of output

8. 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
Memory (RAM)
Compact Disc
Floppy Disk
Tape
Hard Disk
cost
less expensive
more expensive
speed
faster
slower

9. What is capacity?
The number of bytes (characters) a storage medium can hold
Manufacturers use many terms to define the capacity of storage media
Storage Term
Abbreviation
Number of bytes
Kilobyte
Megabyte
Gigabyte
Petabyte KB MB TB GB PB
1 thousand
1 million
1 billion
1 trillion
1 quadrillion
Terabyte

10. 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

11. Floppy Disks 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
liner
shutter
metal hub
magnetic coating
flexible thin film
shell

12. Floppy Disks 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
floppy disk drive

13. Floppy Disks How are floppy disk drives designated? One floppy drive
drive A
Two floppy drives
drive A
drive B

14. Floppy Disks 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

15. Floppy Disks What is density?
Upward compatible
Able to recognize newer media
Floppy disk drives are not upward compatible
Downward compatible
Able to recognize and use earlier media
Floppy disk drives are downward compatible
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

16. Floppy Disks What are tracks and sectors?
sector 18 per track
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
track 80 per side
80 tracks per side X 18 sectors per track X 2 sides per disk X 512 bytes per sector = 1,474,560 bytes

17. Floppy Disks 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
cluster 2 to 8 sectors

18. Floppy Disks What is formatting?
The process of preparing a disk for reading and writing
Formatting marks bad sectors as unusable

19. Floppy Disks How do you care for a floppy?
Avoid exposure to heat and cold
A floppy disk can last at least seven years
Proper care helps to maximize a disk’s life
Avoid exposure to magnetic fields
Avoid exposure to contaminants such as dust, smoke, or salt air
Never open the shutter and touch the disk’s recording surface
Keep disks in a storage tray when not using them

20. Floppy Disks 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
notch closed means you can write on the disk
notch open means you cannot write on the disk
write-protected
not write-protected

21. 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

22. High-Capacity Disks 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
data
instructions
information

23. Hard disk installed in system unit
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
Hard disk installed in system unit

24. 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

25. Clearance is approximately two millionths of an inch
Hard Disks
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
hair
Clearance is approximately two millionths of an inch
read/write head
dust
smoke
gap
platter

26. 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

27. Hard Disks What is a disk cache?
A portion of memory that the processor uses to store frequently accessed items
A cache controller manages cache and thus determines which items cache should store
processor
hard disk
disk cache
second request for data — to hard disk
first request for data — to disk cache
processor
hard disk
disk cache
first request for data — to disk cache
processor
hard disk
disk cache

28. Designation for second partition on the hard disk
Hard Disks
What is a partition?
drive C
Designation for first partition or for a single partition on the hard disk
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
drive D
Designation for second partition on the hard disk

29. Hard Disks What is a disk controller?
USB port
Used as interface for many external hard disk drives
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
Enhanced Integrated Drive Electronics (EIDE)
One of the most widely used controllers
Supports up to four hard disks
small computer system interface (SCSI)
Supports multiple disk drives, as well as other peripherals
You can daisy chain devices together

30. Hard Disks 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

31. 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

32. Compact Discs CD-ROM What is a compact disc (CD)? CD-RW CD-R DVD-ROM
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

33. Compact Discs 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
Push button to slide out the tray
Insert disc, label side up
Push the same button to close the tray

34. 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

35. 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

36. 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

37. 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

38. 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

39. 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

40. DVD-ROMs 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

41. 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

42. 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

43. 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 cart
idges mounted in a separate cabinet called a tape library
Three common types of tape drives

44. Tapes What is sequential access versus direct access?
Method used for tape
Reading and writing data consecutively
You must forward or rewind the tape to a specific point to access a specific piece of data
Much slower
Utilized most often for long-term storage and backup
Direct access
Method used for floppy disks, hard disks, and compact discs
Also called random access
You can locate a particular data item or file immediately, without having to move consecutively through items stored in front of the desired data item or file
Faster
Used as the primary method of storage

45. 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

46. PC Cards What are the uses of PC Cards? Three types of PC Card
Advantage of a PC Card for storage is portability between systems

47. 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

48. Miniature Mobile Storage Media
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

49. Miniature Mobile Storage Media
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

50. Miniature Mobile Storage Media
What are the types of smart cards?
Store data such as photographs, music, books, and video clips
Intelligent smart card contains a processor and has input, process, output, and storage capabilities
Memory card has only storage capabilities
Store a prepaid dollar amount that is updated when the card is used
Store patient records, vaccination data, and other healthcare information
Store tracking information such as customer purchases or employee attendance

51. Miniature Mobile Storage Media
What is electronic money?
A bank issues unique digital cash numbers that represent an amount of money
A means of paying for goods and services over the Internet
Also called digital cash
When you purchase digital cash, the amount of money is withdrawn from your bank account
To use the card you swipe it through a card reader

52. 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
Microfiche
Uses a small sheet of film, usually about four inches by six inches
Microfilm
Uses a 100- to 215-foot roll of film

53. Microfilm and Microfiche
How do life expectancies of various media compare?
Microfilm and microfiche are inexpensive and have the longest life of any storage medium