The Oral TraditionThe Oral Tradition

ATS 315ATS 315

What’s a Virus?What’s a Virus?

A piece of information, stored as A piece of information, stored as DNADNA

What does a virus do?What does a virus do?

What does a virus do?What does a virus do?

• Makes your cells make copies of it!Makes your cells make copies of it!

• Gets YOUR hardware to do the work of Gets YOUR hardware to do the work of following ITS instructions.following ITS instructions.

Characteristics of a VirusCharacteristics of a Virus

• Can’t reproduce without highjacking Can’t reproduce without highjacking hardwarehardware

• Reproduces faithfullyReproduces faithfully

• Has a mechanism for spreading to new Has a mechanism for spreading to new hostshosts

Computer VirusesComputer Viruses

• Need YOUR hardware in order to Need YOUR hardware in order to reproduce and spreadreproduce and spread

• Reproduce faithfully– no mutationsReproduce faithfully– no mutations

• Have mechanisms for spreading to new Have mechanisms for spreading to new hostshosts

Urban LegendsUrban Legends

• ““Eating fish on Fridays during Lent” was Eating fish on Fridays during Lent” was started by a pope to save the fishing started by a pope to save the fishing industry.industry.

Urban LegendsUrban Legends

• ““Eating fish on Fridays during Lent” was Eating fish on Fridays during Lent” was started by a pope to save the fishing started by a pope to save the fishing industry.industry.

• Any different variations?Any different variations?

Urban LegendsUrban Legends

• ““Eating fish on Fridays during Lent” was Eating fish on Fridays during Lent” was started by a pope to save the fishing started by a pope to save the fishing industry.industry.

• How does this spread?How does this spread?

Other ExamplesOther Examples

MemesMemes

• Pieces of information (whether true or Pieces of information (whether true or false) that spread faithfully through a false) that spread faithfully through a population.population.

• Very different from rumors, gossip, Very different from rumors, gossip, “telephone”, etc.“telephone”, etc.

MemesMemes

• JokesJokes

• SongsSongs

• ReligionsReligions

• IdeologiesIdeologies

MemesMemes

• Are perfected by spreading through “The Are perfected by spreading through “The Oral Tradition”—frequent retelling adds Oral Tradition”—frequent retelling adds beneficial (to the meme!) information and beneficial (to the meme!) information and removes unhelpful (to the meme!) removes unhelpful (to the meme!) information.information.

• Examples:Examples:• Sagas, campfire songs, etc.Sagas, campfire songs, etc.

UNIX is a Meme!UNIX is a Meme!

• Spreads by “the oral tradition”– best Spreads by “the oral tradition”– best learned by hearing it from others.learned by hearing it from others.

• Example—How did you learn to play baseball, by Example—How did you learn to play baseball, by reading a book?reading a book?

• Example—How did you learn English, by Example—How did you learn English, by diagramming sentences?diagramming sentences?

UNIX is a Meme!UNIX is a Meme!

• Vast numbers of people have told and Vast numbers of people have told and retold how to work with UNIX.retold how to work with UNIX.

• By evolution, it has been reduced to the By evolution, it has been reduced to the parts that work best.parts that work best.

• Stuff gets added only when the group Stuff gets added only when the group thinks it is a real improvement—i.e., helps thinks it is a real improvement—i.e., helps win converts (“spread”).win converts (“spread”).

The Best Way to LearnThe Best Way to Learn

• You encounter a problem that you want to You encounter a problem that you want to solve.solve.

• You determine that a solution exists You determine that a solution exists already.already.

• You learn what you need to solve the You learn what you need to solve the problem.problem.

Comparison with WindowsComparison with Windows

• Let’s examine how a new feature gets Let’s examine how a new feature gets added to UNIX versus how it gets added added to UNIX versus how it gets added to Windows.to Windows.

• New feature: Instant MessagingNew feature: Instant Messaging

UNIXUNIX

• Demand for the new feature.Demand for the new feature.

• Many different solutions proposed and Many different solutions proposed and written.written.

• Source code is available on the netSource code is available on the net– Everyone can look for bugs, security Everyone can look for bugs, security

problems, etc.problems, etc.

UNIXUNIX

• No deadline—take as long as is needed.No deadline—take as long as is needed.

• Relatively small, cheap hardware means Relatively small, cheap hardware means program will have to be small and efficient.program will have to be small and efficient.

WindowsWindows

• MS notices that the competition has a new MS notices that the competition has a new Instant Messaging program.Instant Messaging program.

• New program must be written in ways that New program must be written in ways that avoid copyright problems.avoid copyright problems.

• New program must be written in ways that New program must be written in ways that are hard for the competition to imitate.are hard for the competition to imitate.

• New program has to be integrated into the New program has to be integrated into the operating system, since that is the operating system, since that is the “product”.“product”.

WindowsWindows

• Program written by engineers who go Program written by engineers who go home at 5 o’clock.home at 5 o’clock.

• Must be done by some deadline for the Must be done by some deadline for the OS to ship.OS to ship.

• Can be a huge, inefficient program, since Can be a huge, inefficient program, since it will be shipped on the newest it will be shipped on the newest computers.computers.

The ResultThe Result

• The Unix program will be small, efficient, The Unix program will be small, efficient, bug-free, secure, etc.bug-free, secure, etc.

• The Windows program will be bulky, The Windows program will be bulky, inefficient, buggy, insecure, etc.inefficient, buggy, insecure, etc.

• Frequent updates of the Windows product Frequent updates of the Windows product will be necessary, whereas the UNIX will be necessary, whereas the UNIX product works!product works!

Of CourseOf Course

• The Windows program is probably:The Windows program is probably:– GUIGUI– Well-documented in the help filesWell-documented in the help files– Used by all your friendsUsed by all your friends

• While the UNIX program is:While the UNIX program is:– TrickyTricky– Command LineCommand Line