1. Computer Files and Data Storage
Section A
Data, Information, and Files
CHAPTER 4
Computer Files and Data Storage
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2. Data, Information, and Files 4
Section A
Data, Information, and Files
Chapter 4
Section PREVIEW
Section D
Section A
You will be able to:
Correctly use the terms “data” and “information”
Create valid file names under DOS and Windows
Explain how wildcards and file extensions simplify file access
Determine if a file is an executable file or a data file
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3. 4 Data and Information: Technically Speaking
Aren’t data and information the same thing?
Chapter 4
Section A
Data is words, numbers, and graphics that describe people, events, things, and ideas.
used by computers
Information is the words, numbers, and graphics used as the basis for human actions and decisions.
used by humans
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4. 4 Computer Files What kinds of files are stored on a computer?
Chapter 4
Section A
File - named collection of data that exists on a storage medium such as a hard disk or floppy drive
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5. 4 File Naming Conventions
May I use any name I want when I create my own files?
Chapter 4
Section A
Filename
unique set of letter and numbers
identifies a file
describes the file contents
Filename extension further describes the file contents.
separated by the filename with a dot
You must provide a valid filename that adheres to rules or file naming conventions.
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6. 4 Wildcards Is * * a filename?
Chapter 4
Section A
The asterisk is a wildcard character used to represent a group of characters in the filename or extension.
Wildcards are handy for finding specific files on a hard disk.
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7. 4 File Extensions and File Types
Why do I need to know about file extensions?
Chapter 4
Section A
You can access files efficiently if you are familiar with the characteristics of file categories.
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8. 4 Executable Files How do I use executable files?
Chapter 4
Section A
An executable file contains the program instructions that tell a computer how to perform a specific task.
Most have .exe or .com extensions.
Executable
files have
.exe file
extensions
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9. 4 Data Files How do I use data files?
Chapter 4
Section A
A data file contains words, numbers, and pictures that you can view, edit, save, send, and print.
Passive, unlike executable files which are active
created using application software
receive data files on CD-ROMS such as clip art
You manipulate a data file using the same software that was used to create it.
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10. 4 Data Files How do I use data files?
Chapter 4
Section A
Section A
The standard method for opening a data file is to start an application, then use the open command.
A generic filename extension indicates general type of data contained in a file.
a .bmp could be opened in Microsoft Paint or MicroGrafx Picture Publisher
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11. 4 Data Files How do I use data files?
Chapter 4
Section A
An application-specific filename extension is associated with a particular application
Application-
specific
filename
extensions
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12. 4 Configuration Files, and Program Modules
What other kinds of files will I find on my computer?
Chapter 4
Section A
Other files are necessary for hardware and software operations and should not be deleted.
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13. Computer Files and Data Storage
Section B
File Manager Utility Software
CHAPTER 4
PARSONS/OJA
Computer Files and Data Storage
Page 168

14. File Manager Utility Software 4
Section B
File Manager Utility Software
Chapter 4
Section PREVIEW
Section D
Section B
You will be able to:
Describe the difference between logical and physical file storage
Page 168

15. File Manager Utility Software 4
Section B
Worksheets
File Manager Utility Software
Chapter 4
Section B
File manager utility software
provided by your computer operating system
helps you locate, rename, move, copy and delete files
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16. 4 Device Letters Why do storage devices have letters?
Chapter 4
Section B
A storage device, such as a floppy disk drive, a hard drive, and a CD-ROM drive, is identified by a letter called a device letter.
floppy disk drive = A
main hard disk = C
additional storage devices = D through Z
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17. 4 Directories and Folders
How can I get a list of files that are stored on a disk?
Chapter 4
Section B
Section B
An operating system maintains a list of files called a directory for each disk, CD-ROM or DVD.
Directory includes
filename
filename extension
date and time file was created
file size
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18. 4 Directories and Folders
How can I get a list of files that are stored on a disk?
Chapter 4
Section B
Section B
Operating
system’s
file manager
utility displays
lots of information
about the files
stored on a
computer
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19. 4 Directories and Folders
How can I get a list of files that are stored on a disk?
Chapter 4
Section B
Section B
Root directory
main directory of a disk
provides a useful list of files
Folders - smaller lists within directories
A folder is separated from a drive letter and a filename by a backslash (\).
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20. 4 Directories and Folders
How can I get a list of files that are stored on a disk?
Chapter 4
Section B
Section B
A file specification (path) is the drive letter, folder, filename, and extension that identifies a file.
A:\Word\Gumbo.doc
drive letter
extension
filename
subdirectory (folder)
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21. Storage Models
How does file manager utility software depict files and folders?
Chapter 4
Section B
File manager utility software provides a metaphorical view of the files stored on a computer.
also called logical models
filing cabinet
tree structure
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22. Storage Models
How does file manager utility software depict files and folders?
Chapter 4
Section B
A file cabinet
metaphor depicts a
storage device as a
drawer of a filing
cabinet containing
folders and documents.
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23. Storage Models
How does file manager utility software depict files and folders?
Chapter 4
Section B
Visualize a disk directory as a tree.
trunk and branches are folders
leaves are files
You can visualize
the directory
of a disk as a
tree on its side.
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24. Storage Models
How does file manager utility software depict files and folders?
Chapter 4
Section B
Windows
Explorer
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25. 4 Using File Manager Utility Software
How do I use file manager utility software?
Chapter 4
Section B
Find - to locate a file
Rename - to change the name
Copy - to copy a file
Move - to move file from one folder to another
Delete - when you no longer need a file
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26. Computer Files and Data Storage
Section C
How Computers Store File Data
CHAPTER 4
Computer Files and Data Storage
Page 174

27. 4 Section C How Computers Store File Data Section PREVIEW
Chapter 4
Section PREVIEW
Section D
Section C
You will be able to:
Describe the difference between logical and physical file storage
Discuss how the directory and the FAT help you access files
Page 174

28. 4 Section C How Computers Store File Data
Chapter 4
Section C
The data for a single file can be scattered all over the surface of a disk.
Physical storage - way computer store data on a disk.
Logical storage - conceptual model of files and folders.
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29. Storage Terminology
What are the basic components of a data storage system?
Chapter 4
Section C
Storage medium - the disk, tape, CD, DVD, paper, or other substance that contains data
Storage device - mechanical apparatus that records and retrieves data from a storage medium
floppy disk drives
hard disk drives
CD drives
DVD drives
tape drives
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30. Storage Terminology
What are the basic components of a data storage system?
Chapter 4
Section C
Storage technology - a storage device and the media it uses.
Storing - also known as
writing data (mainframe applications)
saving a file (Windows terminology)
Retrieving - also known as
reading data (mainframe applications)
loading data
opening a file (Windows terminology)
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31. Bits and Bytes
If I enter a letter or number how is it actually stored?
Chapter 4
Section C
Computers use codes to convert information into digital data.
series of 1s and 0s
Bit - smallest unit for digitizing data
Byte - 8 bits
A byte represents:
a character
a space
numeral
punctuation
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32. 4 Magnetic and Optical Technologies
How does a computer get the 1s and 0s onto the storage medium?
Chapter 4
Section C
1s and 0s are changed in the surface of the storage medium.
Transformation depends on storage technology.
Magnetic storage - stores data by magnetizing microscopic particles on the disk or tape surface
Read-write head - mechanism in the disk drive that reads and writes magnetized particles that represent data
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33. 4 Magnetic and Optical Technologies
How does a computer get the 1s and 0s onto the storage medium?
Chapter 4
Section C
Disk surface
Read-write head
Storing data on
magnetic
media
Mylar disk
Page 175

34. 4 Magnetic and Optical Technologies
How does a computer get the 1s and 0s onto the storage medium?
Chapter 4
Section C
Data stored on magnetic media such as floppy disks can be altered by dust, smoke, heat, and mechanical problems.
Some experts estimate that the reliable life span of data stored on magnetic media is about three years.
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35. 4 Magnetic and Optical Technologies
How does a computer get the 1s and 0s onto the storage medium?
Chapter 4
Section C
Optical storage stores data as microscopic light spots (lands) and dark spots (pits) on the disk surface.
Data stored on an optical storage device is less susceptible to environmental damage.
Page 176

36. 4 Magnetic and Optical Technologies
How does a computer get the 1s and 0s onto the storage medium?
Chapter 4
Section C
Optical
storage devices
read data
using reflected
laser light
Page 176

37. 4 Tracks, Sectors, and Clusters
Is data stored in specific places on a disk, tape, or CD?
Chapter 4
Section C
Tracks - electronic storage bins
parallel to the edge of the tape
spiral out from the center of the disk
arranged as concentric circles or
Tracks that are arranged in concentric circles are divided into wedge-shaped sectors
Cluster - a group of sectors
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38. 4 Tracks, Sectors, and Clusters
Is data stored in specific places on a disk, tape, or CD?
Chapter 4
Section C
A formatted
disk is
divided into
circular
tracks
Page 177

39. 4 File Allocation Tables
How does a computer keep track of the location of every file?
Chapter 4
Section C
File allocation table (FAT) - an operating system file that maintains a list of files and their physical location on the disk.
like a table of contents
a damaged FAT results in losing data
Back up data on hard disk.
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40. 4 File Allocation Tables
How does a computer keep track of the location of every file?
Chapter 4
Section C
Computer looks for empty clusters to store data
Name of new file and number of cluster are recorded in the FAT
Files that do not fit in one cluster spill over to contiguous or noncontiguous clusters, depending on availability.
Pointers - instructions that point to each piece of the file
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41. 4 File Allocation Tables
How does a computer keep track of the location of every file?
Chapter 4
Section C
Section C
Each colored
cluster
represents
part of a file
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42. 4 File Allocation Tables
How does a computer keep track of the location of every file?
Chapter 4
Section C
It takes longer to retrieve a file stored in noncontiguous clusters.
When you delete a file, the clusters’ status becomes “empty” but retains old data until new data is stored.
You may be able to retrieve data using an undelete utility.
Recycle Bin’s Restore feature
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43. 4 File Allocation Tables
How does a computer keep track of the location of every file?
Chapter 4
Section C
Files stored in many noncontiguous clusters become fragmented.
drive performance declines
becomes harder to locate clusters
A defragmentation utility rearranges files in contiguous clusters
improves drive performance
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44. Computer Files and Data Storage
Section D
Disks, Tapes, CDs, and DVDs
CHAPTER 4
Computer Files and Data Storage
Page 180

45. 4 Section D Disks, Tapes, CDs, and DVDs Section PREVIEW
Chapter 4
Section PREVIEW
Section D
Section D
You will be able to:
Select a storage device based on characteristics such as its capacity and access speed
Page 180

46. 4 Section D Disks, Tapes, CDs, and DVDs
Chapter 4
Section D
There are many types of storage devices, each with unique advantages and disadvantages.
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47. 4 Section D Disks, Tapes, CDs, and DVDs Versatility
Chapter 4
Section D
Versatility
can access data from different media
Durability
less susceptible to damage
Storage capacity - maximum amount of data that can be stored on a storage medium
kilobyte = approximately 1000 bytes
megabyte = approximately 1 million bytes
gigabyte = approximately 1 billion bytes
terabyte = approximately 1 trillion bytes
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48. 4 Section D Disks, Tapes, CDs, and DVDs
Chapter 4
Section D
Speed - measured by access time and data transfer rate
Access time - average time it takes a computer to locate data and read it
millisecond = one-thousandth of a second
Random access - ability of a device to jump directly to the track or sector holding the data
floppy disk, hard drive, CD, DVD
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49. 4 Section D Disks, Tapes, CDs, and DVDs
Chapter 4
Section D
Sequential access - reads through from beginning of tape
tape drive
Data transfer rate - amount of data that moves per second
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50. 4 Floppy Disk Storage Why is it called a floppy disk?
Chapter 4
Section D
Floppy disk - round piece of flexible mylar plastic covered with thin layer of magnetic oxide.
sealed in protective casing
also called floppies or diskettes
inside casing is “floppy”
not as speedy as zips
decreased use
Zip disk - high-capacity floppy disk manufactured by Iomega Corporation.
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51. 4 Floppy Disk Storage Why is it called a floppy disk?
Chapter 4
Section D
Double-sided disk - stores twice as much as single-sided
Disk density - closeness and size of magnetic particles it stores
High-density disk - stores more data than double-density
Page 182

52. 4 Floppy Disk Storage Why is it called a floppy disk? Disk capacities
Chapter 4
Section D
Disk
capacities
Page 182

53. Hard Disk Storage
How can a hard disk be the same size as a floppy, but store so much more data?
Chapter 4
Section D
Hard disk platter - a flat, rigid disk made of aluminum or glass and coated with magnetic oxide
density far exceeds floppy disk
Hard disk - one or more platters and their associated read-write heads.
preferred type of main storage
Cylinder
vertical set of tracks
basic storage bin for hard disk drive
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54. Hard Disk Storage
How can a hard disk be the same size as a floppy, but store so much more data?
Chapter 4
Section D
Hard disk
platters prevent
dust from
interfering with
read-write
heads
Page 183

55. Hard Disk Storage
How can a hard disk be the same size as a floppy, but store so much more data?
Chapter 4
Section D
Hard disks
provide random access to files
faster than floppy disk access
continually in motion
Page 184

56. Hard Disk Storage
How can a hard disk be the same size as a floppy, but store so much more data?
Chapter 4
Section D
Head crash - when a read-write head runs into a dust particle or other contaminant on the disk.
head crash damages some data on disk
triggered by jarring the hard disk while in use
Removable hard disk - hard disks that can be inserted and removed from drive
increase storage capacity
provides security for data
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57. Hard Disk Storage
How can a hard disk be the same size as a floppy, but store so much more data?
Chapter 4
Section D
RAID - (redundant array of independent disks)
type of hard disk storage
found on mainframe and microcomputer installations
contains many disk platters
provides redundancy
faster data access
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58. Hard Disk Storage
How can a hard disk be the same size as a floppy, but store so much more data?
Chapter 4
Section D
Disk cache
special area of computer memory
computer transfers data you are likely to need
reads data from nearby sectors and stores it in the cache
Page 185

59. Tape Storage
Do they still use those big tape drives on computers that you see in old movies?
Chapter 4
Section D
Tape
most popular form of storage in 1960s
continued in form of cassette tape drive
requires sequential access
inconvenient and slow
Recent revival in tape storage for backing up data, not for principal storage device.
Tape backup - copy of data on hard disk stored on magnetic tape.
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60. Tape Storage
Do they still use those big tape drives on computers that you see in old movies?
Chapter 4
Section D
Open reel tapes
large reels seen in old movies
access speeds measured in seconds
still used as distribution medium for some mainframe and minicomputer systems
Tape cartridge - a removable magnetic tape module similar to a cassette tape.
Page 187

61. CD-ROM Technology
If CD-ROMS are read only, doesn’t that limit their use?
Chapter 4
Section D
CD-ROM
stands for Compact Disc Read-Only Memory
data stamped on when manufactured
holds up to 680 MB
coated with clear plastic, durable
estimated life exceeds 500 years
inexpensive to manufacture
ideal for distribution of large files
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62. CD-ROM Technology
If CD-ROMS are read only, doesn’t that limit their use?
Chapter 4
Section D
CD-ROMS
choice for delivery of multimedia applications
read-only storage memory
Read-only - computer can retrieve from it but not save new data on it
CD-ROM drives
standard on today’s computers
speeds up to 40X
Page 188

63. 4 CD-R Technology Can I make my own CD-ROMs? CD-R
Chapter 4
Section D
CD-R
stands for compact disc-recordable
allows you to create your own CDs by recording on a CD-R disk
Recording is done on a CD-R drive
uses a laser to change the reflectivity of a dye layer on a blank CD-R disk.
Page 189

64. 4 CD-R Technology Can I make my own CD-ROMs?
Chapter 4
Section D
Disks produced on CD-R drive
can be used on CD-ROM and DVD drives
cannot be erased or modified
some drives have multisession support (can record in multiple sessions)
available after 1998
Archiving - moving data that is not accessed frequently off of a primary storage device
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65. 4 CD-RW Technology Is there any way to change the data on a CD?
Chapter 4
Section D
CD-RW (compact disc-rewritable) allows you to write on a CD, then change the data
requires special CD-RW disks
requires special CD-RW drive
requires phase change technology
Phase change technology - alters the crystal structure on the disk surface
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66. 4 DVD Technology How is DVD different from CD technology?
Chapter 4
Section D
DVD (digital video disc or digital versatile disc)
variation of CD technology
designed to provide enough storage capacity for a full length movie
will replace video tape (experts believe)
DVD-ROM disk
stamped with data when manufactured
cannot change or add data
stores 4.7 GB
ideal for games, maps, large databases
Page 190

67. 4 DVD+RW and DVD-RAM Technology Is there a DVD equivalent to CD-RW?
Chapter 4
Section D
DVD+RW
uses phase change technology
cannot be used on DVD-RAM
DVD-RAM
uses a blend of technologies to record data
cannot be used on DVD+RW
Both DVD+RW and DVD-RAM can be read on DVD-ROM drives.
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