comp4 unit4c lecture slides

Introduction to Information and Computer ScienceComputer Software

Lecture cThis material (Comp4_Unit4c) was developed by OHSU, funded by the Department of Health and Human Services, Office of

the National Coordinator for Health Information Technology under Award Number [IU24OC000015].

Computer SoftwareLearning Objectives

• Define application vs. system software. (Lecture a)• Give examples of application software focusing on

healthcare systems. (Lecture a)• Describe the functions of system software. (Lecture b)• List different types of operating systems. (Lecture b)• Explain the purpose and usage of file systems.

(Lecture c)

Health IT Workforce Curriculum Version 3.0/Spring 2012

2Introduction to Information and Computer Science Computer Software

Lecture c

File System

• A file system is a way of organizing files and their data on a storage device

• An operating system includes a file system– OS serves as intermediary between file

system and applications– Applications include software, OS utilities, etc.



Lecture c

Files• Files are blocks of program

instructions or data stored on disk• File types

– Executable (machine code instructions)

– Text file (collection of characters)– Special format

• Particular to an application (e.g., Microsoft® Word, Excel)

• Format for storing images, videos, etc.• Format for archives



Lecture c

(clker.com, 2010, PD-US)

File Names and Extensions• Every file must have a name

– Each OS has its own naming rules– May or may not be case-sensitive

• The file extension is the portion of the name after “.”– Identifies the file type– Used to identify what you can do with the file– May not see the extension

• Examplesessay.docbudget.xlswinzip.exephoto1.jpg



Lecture c

File Permissions

• Files have owners• Files have permissions

– Identify if the file can be read (opened)– Identify if the file can be written (saved)– Identify if the file is an executable program (a

program that can be run)• Permissions may vary by user

– One user may only be able to read a file, another may be able to read and write

– Important security measure



Lecture c

File Size

• All files have a size• Expressed in bytes (or KB or MB or GB)• Size depends on the amount of data stored in

the file– A long Word document will be larger than a short

one– An HD video will be larger than a low resolution

video– A high resolution image will be larger than a

simple text file (unless the text file is really, really long)



Lecture c

Organizing Groups of Files

• Most file systems provide ways to organize your files into “containers”– In Windows and Mac OS the containers are called

folders– In Unix® and Linux, the containers are called

directories– Folders/directories contained within other

folders/directories are called subfolders/subdirectories

• A flat file system has only one large directory or folder



Lecture c


File Management Utilities• Operating systems provide utilities for the user to

manage files and folders/directories– Microsoft Windows® Explorer– Mac OS X Finder– Typed commands in Unix

• Allow user to– View files and properties– Find files– Move files– Copy and paste files– Rename files– Create folders/directories



Lecture c

Microsoft Windows File Explorer

(Windows Vista®, 2009, with permission from Microsoft )



Lecture c

Mac OS X Finder

(Apple Inc., 2009, WP: FUR)



Lecture c

http://upload.wikimedia.org/wikipedia/en/0/00/Finder.png

Dolphin File ManagerKDE® Windows for Linux

(KDE®, 2008, GNU-GPL)



Lecture c

http://upload.wikimedia.org/wikipedia/commons/e/ee/KDE_4.0.png

Application File Utilities

• These file utilities are available within applications, too

• Facilitate moving, deleting, copying, opening, and saving files



Lecture c

(Sven, 2008, GNU-GPL)

File System Hierarchy• File systems that

are not flat have a hierarchy– A tree like structure

that represents nested subfolders/ subdirectories

(Che, 2005, GNU-GPL)



Lecture c

Other File Utilities

• Search• File compression/archiving

utilities– Windows compression utilities– WinZip– Stuffit

• Backup and restore utilities

• Security utilities• File transfer utilitiesHealth IT Workforce Curriculum Version 3.0/Spring 2012

15

Introduction to Information and Computer Science Computer Software

Lecture c

(clker.com, 2007 – 2010, PD-US)

File System Implementation

• Different types of file systems– Disk File System– Flash File System– Network File System

• The logical model (Explorer/Finder) is different from the physical model (hard disk)



Lecture c

Hard Disk Drive

• A hard disk drive contains a platter where data is stored

• The spindle holds one or more platters

• The platter spins and the arm moves so that the head is over the location on disk to be read/written

(Surachit, 2007, CC BY-SA 3.0)



Lecture c

http://upload.wikimedia.org/wikipedia/commons/5/52/Hard_drive-en.svg

Disk File Storage

• Files are stored physically in sectors (C) on the platter (usually 512 bytes)

• Sectors make up a track (A)• Groups of adjacent sectors are

called clusters (D)• Each sector and track has an

address



Lecture c

(Heron2/MistWiz, 2008, PD-US)

Formatting Disk

• Disks must be formatted before they can be used– Separated into tracks and sectors– Given addresses

• Most disks come pre-formatted• May need to reformat later



Lecture c

File Systems• Serve as an interface to the storage

device (disk drive)• Keep track of where files are located

– File name and its address on disk– Kept in an index

• Optimize speed of storing and retrieving data– Uses clusters of sectors– Keeps track of free clusters

• Files may be stored in non-contiguous clusters– Called fragmented files– Can be slow to access



Lecture c


File Systems (continued)

• What happens when a file is deleted?– File system removes file from index– Identifies clusters as free

• Can sometimes be recovered– Must do it quickly

• Can use file shredder utilities to overwrite clusters

• In healthcare, old disks must be safely disposed



Lecture c

Disk File System Examples

• FAT (File Allocation Table)– Simple file system without file security– FAT12, FAT16, FAT32– Used in Microsoft OS before Windows NT – Used on flash cards today

• NTFS (NT File System)– Complex file system with file security– Used in Microsoft Windows starting with version NT



Lecture c

File System Examples (continued)

• HFS, HFS+, HFSX (Hierarchical File System)– Mac OS and Mac OS X– HFS was similar to FAT16– HFS+ and HFSX introduced file security

• ext family, XFS– Linux– Provides file security and access control

Note: one OS can support multiple file systems



Lecture c

Putting It All Together

• The application or the user performs a file operation (open, close, read, write)

• The operating system translates that operation into one understood by the file system

• The file system finds the file and performs the operation. If any data is returned, it’s sent to the OS.

• The OS returns any data to the application or user



Lecture c

File Management Tips• Use descriptive names for files and folders/directories• Maintain proper file extensions • Group similar files together• Organize folders/directories in a proper hierarchy• Delete or archive files you no longer need• Defragment drive regularly• Maintain enough free space (20%) on drive• Back up!



Lecture c


Computer SoftwareSummary - Lecture c

• File systems• File types• File sizes• Permissions• File organization on a hard drive

26Health IT Workforce Curriculum Version 3.0/Spring 2012

Introduction to Information and Computer Science Computer Software

Lecture b

Computer Software Summary• Software is instructions for the hardware• Application software makes computers productive

and entertaining for users• Operating systems coordinate applications and

hardware• Operating systems are on every computer from

PCs to smart phones to embedded computers• File systems manage the storage and retrieval of

files stored on disk



Lecture c

Computer SoftwareReferences – Lecture c

References • Computer File. (2011). Retrieved 24 March 2011 from Wikipedia: http://en.wikipedia.org/wiki/Computer_file. • Evans A, Martin K, Poatsey MA. (2010). Chapter 5: Using System Software: The Operating System, Utility

Programs and File Management. In: Technology in Action: Complete. 7th ed. New Jersey: Prentice Hall;. • File Allocation Table. (2011). Retrieved 24 March 2011 from Wikipedia:

http://en.wikipedia.org/wiki/FAT_file_system. • File Systems. (2011). Retrieved 24 March 2011 from Wikipedia:. http://en.wikipedia.org/wiki/File_system. • Hard Disk Drive. (2011). Retrieved 24 March 2011 from Wikipedia: http://en.wikipedia.org/wiki/Hard_disk_drive. • HFS Plus. (2011). Retrieved 24 March 2011 from Wikipedia: http://en.wikipedia.org/wiki/HFS_Plus. • Hierarchical File System. (2011). Retrieved 24 March 2011 from Wikipedia:

http://en.wikipedia.org/wiki/Hierarchical_File_System.• Microsoft Technet. (2011) Chapter 17: Disk and File System Basics. In Windows NT Workstation Resource Kit.

Retrieved from: http://technet.microsoft.com/en-us/library/cc750198.aspx.• Morley Deborah, Parker Charles S. (2011) Chapter 6: System Software: Operating Systems and Utility

Programs. In: Understanding Computers Today and Tomorrow. 12th ed. Boston: Course Technology.• NTFS. (2011). Retrieved 24 March 2011 from Wikipedia: http://en.wikipedia.org/wiki/Ntfs.• Parsons JJ, Oja D. (2011). Chapter 4: Operating Systems and File Management. In: New Perspectives on

Computer Concepts 2011: Comprehensive. 13th ed. Boston: Course Technology.• Shelley GB, Vermaat ME. (2011). Chapter 8: Operating Systems and Utility Programs. In: Discovering Computers

2011: Introductory. 1st ed. Boston: Course Technology.



Lecture c

http://en.wikipedia.org/wiki/Computer_file

http://en.wikipedia.org/wiki/FAT_file_system

http://en.wikipedia.org/wiki/File_system

http://en.wikipedia.org/wiki/Hard_disk_drive

http://en.wikipedia.org/wiki/HFS_Plus

http://en.wikipedia.org/wiki/Hierarchical_File_System

http://technet.microsoft.com/en-us/library/cc750198.aspx

http://en.wikipedia.org/wiki/Ntfs


Images• Slide 3: Binary File Image [image on the Internet]. c 2010 [Updated 8/13/2010; cited 11/8/2011]. Available from:

http://www.clker.com/clipart-binary-file.html. (PD-US).• Slide 8: Folder Image [image on the Internet]. c 2007 [Updated 11/13/2007; cited 11/8/2011]. Available from:

http://www.clker.com/clipart-3618.html. (PD-US). • Slide 10: Screenshot of Windows Explorer in Windows Vista® [image on the Internet]. Used with permission from

Microsoft (c 2009). [Updated 9/6/2009; cited 11/8/2011]. Available from: http://en.wikipedia.org/wiki/File:Windows_Explorer_Vista.png.

• Slide 11: Mac OS X Finder Image [image on the Internet]. Apple Inc. (c 2009). [Updated 8/8/2009; cited 11/8/2011]. Available from: http://en.wikipedia.org/wiki/File:Finder.png. (WP:FUR).

• Slide 12: KDE® Dolphin Image [image on the Internet]. KDE® (c 2008). [Updated 8/2/2008; cited 11/8/2011]. Available from: http://en.wikipedia.org/wiki/File:KDE_4.0.png. (GNU-GPL).

• Slide 13: Drag and Drop Image [image on the Internet]. Sven (c 2008). [Updated 8/5/2008; cited 11/8/2011]. Available from: http://wikimediafoundation.org/wiki/File:Drag-and-drop-en.svg. (GNU-GPL).

• Slide 14: Directory Tree Image [image on the Internet]. Che (c 2010). [Updated 1/19/2010; cited 11/8/2011]. Available from: http://wikimediafoundation.org/wiki/File:Directory_tree.png. (GNU-GPL).

• Slide 15: Magnifying Glass Image [image on the Internet]. c 2007 [Updated 11/13/2007; cited 11/8/2011]. Available from: http://www.clker.com/clipart-8173.html. (PD-US).

• Slide 15: Compress Image [image on the Internet]. c 2007 [Updated 11/13/2007; cited 11/8/2011]. Available from: http://www.clker.com/clipart-7593.html. (PD-US).



Lecture c

http://www.clker.com/clipart-binary-file.html

http://www.clker.com/clipart-3618.html

http://en.wikipedia.org/wiki/File:Windows_Explorer_Vista.png

http://en.wikipedia.org/wiki/File:Finder.png

http://en.wikipedia.org/wiki/File:KDE_4.0.png


Images• Slide 15: Shield Image [image on the Internet]. c 2010 [Updated 10/27/2010; cited 11/8/2011]. Available from:

http://www.clker.com/clipart-shield-icon.html. (PD-US). • Slide 17: Hard Disk Image [image on the Internet]. Surachit (c 2008). [Updated 12/20/2009; cited 11/8/2011].

Available from: http://en.wikipedia.org/wiki/File:Hard_drive-en.svg. (CC BY-SA 3.0). • Slide 18: Disk structure Image [image on the Internet]. Heron2/MistWiz (c 2008). [Updated 3/5/2008; cited

11/8/2011]. Available from: http://commons.wikimedia.org/wiki/File:Disk-structure2.svg. (PD-US). • Slide 20: File Cabinet Image [image on the Internet]. c 2010 [Updated 6/22/2010; cited 11/8/2011]. Available

from: http://www.clker.com/clipart-system-file-manager.html. (PD-US).• Slide 25: String on finger Image [image on the Internet]. c 2011 [Updated 5/9/2011; cited 11/8/2011]. Available

from: http://www.clker.com/clipart-reminder.html. (PD-US).



Lecture c

comp4 unit4c lecture slides

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