Computer Science 109:
Computers in Our World

Fall 2005
Princeton University

Brian Kernighan
Computer Science Dept.

Thu Feb 2 11:12:21 EST 2006

final answers

final exam schedule    course summary    last year's final exam    answers.

Lecture notes:    9/19    9/21    9/26-28    10/3-5    10/10    10/12    10/17-19    10/24    10/26    11/7    11/9    11/14    11/16    11/21-23    11/30    12/5    12/7    12/12    12/14   

Problem sets:    1     2     3     4     5     6     7     8    

Solutions:    1     2     3     4     5     6     7     8    

Labs:    1     2     3     4     5     6     7     8    

Old stuff:    playlist    survey results    lab assistants    origin of smileys    binary-decimal-hexadecimal-ascii converter    toy machine simulator    ESP    2004 midterm    2004 answers    iPod flea    final exam schedule    2005 midterm answers    Javascript examples    US Patent Office    open document formats    Wired's software bugs    OED definition of bug    a real bug    Top 500 supercomputers    Foreign Affairs article    Diebold parody    COS 109 fashions    Cringely on Internet futures    Enigma page    RSA factoring challenge    Harvard CS E-1    Google article    another Google article    Touretzky's Gallery of CSS Descramblers    how MP3 works    RF spectrum chart   

Problem sets, labs and announcements will be posted only on the web page.
You are responsible for monitoring the web page frequently.

Course summary, schedule and syllabus    What was covered in 2004
      Comparison of COS 109, 111 and 126
Administrivia:    Office hours   Labs   Problem Sets   Exams   Lateness Policy   Collaboration Policy   Textbook
Bibliography

Course Summary

Computers, computing, and many things enabled by them are all around us. Some of this is highly visible, like personal computers and the Internet; much is invisible, like the computers in gadgets and appliances and cars, or the programs that fly our planes and keep our telephones and power systems and medical equipment working, or the myriad systems that quietly collect and share personal data about us.

Even though most people will not be directly involved with creating such systems, everyone is strongly affected by them. COS 109 is intended to provide a broad, if rather high level, understanding of how computer hardware, software, networks, and systems operate. Topics will be motivated by current issues and events, and will include discussion of how computers work; what programming is and why it is hard; how the Internet and the Web operate; security, privacy, and property rights. We will also touch on fundamental ideas from computer science, and some of the inherent limitations of computers.

This course is meant for humanities and social sciences students who want to understand how computing works and how it affects the world they live in. No prior experience with computers is assumed. There are no prerequisites. COS 109 satisfies the QR requirement.

The labs are complementary to the classroom work, and are based on the Internet and the web. Students will construct their own home pages in the first few weeks. They will then add to them throughout the semester, while exploring a spectrum of practical applications, including graphics and sound. Two of the labs are a gentle introduction to programming in Javascript.

The course will have fundamentally the same structure as in previous years, but lectures, case studies and examples change every year according to what's happening. For example, the technical and legal issues around file sharing, digital rights management and intellectual property are very much in the news today. Privacy and security are of increasing importance in an era of viruses, spyware, phishing and identity theft. Search engines have moved from curiosities to highly competitive and profitable businesses.

Schedule 

	 S  M Tu  W Th  F  S
Sep	11 12 13 14 15 16 17
	18 19 20 21 22 23 24	first class
	25 26 27 28 29 30	problem set 1 due; lab 1 due
Oct	                   1
	 2  3  4  5  6  7  8	problem set 2 due; lab 2 due
	 9 10 11 12 13 14 15	problem set 3 due; lab 3 due
	16 17 18 19 20 21 22	problem set 4 due; lab 4 due
	23 24 25 26 27 28 29	takehome midterm due (no lab or problem set)
	30 31			fall break
Nov	       1  2  3  4  5
	 6  7  8  9 10 11 12	problem set 5 due; lab 5 due
	13 14 15 16 17 18 19	problem set 6 due; lab 6 due
	20 21 22 23 24 25 26	Thanksgiving (starts Thu, not Wed)
	27 28 29 30
Dec	             1  2  3	problem set 7 due; lab 7 due
	 4  5  6  7  8  9 10	problem set 8 due; lab 8 due
	11 12 13 14 15 16 17	last class
	18 19 20 21 22 23 24	winter break
	25 26 27 28 29 30 31
Jan	 1  2  3  4  5  6  7
	 8  9 10 11 12 13 14	Q/A session
	15 16 17 18 19 20 21	final exam sometime
	22 23 24 25 26 27 28
	29 30 31

Syllabus

This will evolve over the semester, so check it out from time to time.

Sep 19, 21:    Introduction. What's in a computer

  • Reading: (1) A famous 1945 article by Vannevar Bush, As we may think, is often cited as predicting the Internet and the web. Think about how Bush's "Memex" relates to Google and your PC. (2) Metro-Goldwyn-Mayer v. Grokster is a highly relevant and recent Supreme Court decision involving old issues in a modern setting. Read the Syllabus (first four pages) and skim the first 10 or so pages of the actual decision to get the essence of the technical description and the legal reasoning; the former is what we talk about in this class, and the latter is why it matters. (3) Wikipedia has useful articles on bits, bytes, and binary, among many other things.
  • Problem set 1, due Sep 28

    Sep 26, 28:    How does it work. Representation of information

  • Reading: Preliminary discussion of the logical design of an electronic computing instrument. Original article by Burks, Goldstine and von Neumann. The first page is a remarkably clear description of how computers are organized, though in archaic terminology. No need to read much beyond that, though section 3 is also quite germane.
  • Lab 1: Windows, SSH, mail, file transfer, a first web page
  • Problem set 2, due Oct 5

    Oct 3, 5:    What are the components and how are they made.

  • Reading: Intel web pages on How microprocessors work, how chips are made, and Moore's Law.
  • Lab 2: HTML and web page design
  • Problem set 3, due Oct 12

    Oct 10, 12:    Software and algorithms

  • Reading: a Wikipedia article on algorithms.
  • Lab 3: Advanced HTML
  • Problem set 4, due Oct 19

    Oct 17, 19:    Languages, programming; Javascript

  • Reading: some Javascript tutorials, out of many: one, two, three.
  • Lab 4: Graphics
  • Problem set 5, due Nov 9

    Oct 24, 26:    Javascript. Operating systems

  • Reading: Professor Michael Mahoney's 1998 Freshman seminar on The World of the Computer points to a good collection of interesting reading, including an oral history of Unix.
  • Neal Stephenson's essay on operating systems, updated: The Command Line in 2004.
  • Take-home midterm, due Oct 28 at 5 PM. To be handed out in class on Oct 24.   
  • No lab, no problem set due this week.

    [fall break]

    Nov 7, 9:    File systems, information storage. Applications.

  • Reading: These articles describe some of the realities of software development: Patriot missile defense system failure, a GAO report; A Bug and a Crash, by James Gleick (who has written numerous other fine technical articles); the Therac-25 accidents (long and very scary); a Mars Rover software problem (more technical, very recent). Skim these and think about the many computer systems that we rely on.
  • Lab 5: Introduction to Javascript / Programming fundamentals
  • Problem set 6, due Nov 16

    Nov 14, 16:    Networks & communications, Internet

  • Reading: Skim some of the Internet history papers
  • Lab 6: More Javascript / user interfaces
  • Problem set 7, due Nov 30:   

    Nov 21, 23:    World Wide Web

  • Reading: browse around in some ancient Web history
  • Lab 7: Spreadsheets
  • Problem set 8, due Dec 7

    Nov 28, 30:    Cookies and viruses; security and privacy

  • No problem set or lab this week, but there is class on Nov 23.
  • Reading: what do they know about you? -- general information on privacy; the Electronic Privacy Information Center is also informative. Here's an entertaining view of the future.

    Dec 5, 7:    Cryptography; Compression & error detection.

  • Reading: FAQ on cryptography. The Heavenly Jukebox, by Charles Mann, an excellent article from the middle of the Napster era, circa 2000. Think about how much has changed since, and how much is the same, but amplified. Music everywhere, a good article about digital audio from IEEE Spectrum.
  • Lab 8: Privacy

    Dec 12, 14:    Intellectual property. Case studies. Wrapup

  • Reading: The Chilling Effects Clearinghouse is an excellent, authoritative site dealing with the legal issues around free speech, intellectual property, and online activities. The Electronic Frontier Foundation and Greplaw also have good coverage of these issues. Finally, Your Rights Online at Slashdot points to numerous stories about online rights.
  • No more labs or problem sets!

    [winter break]

    Jan 9:    Q/A session at regular class time.

    Jan 27:    Final exam 9:00 am, McCosh 62 & 64   

  • Note that this date is set by the registrar and I can't make any individual arrangements. Take this into account when making travel plans.
  • Registrar's Official Exam Schedule page.

    Administrative Information

    Lectures: Monday and Wednesday 11:00-12:20, Friend Center  008.

    Professor: Brian Kernighan, 311 CS Building, 609-258-2089, bwk at cs dot princeton dot edu. Office hours Monday and Tuesday 2:30-4:00, or by appointment, or just drop in if my door is open, which it usually is.

    Teaching Assistants:
        Jordan Boyd-Graber jbg@ Thu 4:30-5:30 CS 415
        Matt Hoffman mdhoffma@ Tue 8:30-9:30pm CS 103A
        Janek Klawe jklawe@ Mon 1:30-2:30 CS 316

    Send mail to cos109@princeton.edu with any questions any time.

    Labs:

    There will be eight labs to give hands-on practice in important aspects of computing. The labs are designed to be easily completed within three hours, if you have read through the instructions beforehand, which should take at most an hour. Assistants will be available to help out during scheduled lab sections. Labs are held in the Friend Center; many can be done in dorm rooms or campus clusters, but there will be lab assistants to help out in Friend, and no help elsewhere.

    Labs are together worth about 20 percent of the course grade. To receive credit, students must complete labs by 5:00 PM Friday of the week they are assigned, unless there are extraordinary circumstances.

    Labs start the week of Monday, September 26. There will be no labs in the week before fall break, Thanksgiving week, or the last week of classes. Lab sessions are Monday and Tuesday at 1:30 and Monday through Wednesday at 7:30 in Friend 005 (except Monday afternoon, now in Friend 007).

    Problem sets:

    Eight weekly problem sets, together worth about 20 percent of the course grade, will be assigned. Problems are intended to be straightforward, reinforcing material covered in class and providing practice in quantitative reasoning, and should take 1-2 hours to complete.

    Problem set solutions will be due by 5:00 PM Wednesday, one week after they are assigned. Turn in solutions in the box outside room 311 on the third floor of the CS building, or at the beginning of class. There will be no problem set due in the week before Fall recess (midterm instead) or the last week of the term. No credit can be given for late submissions unless there are extraordinary circumstances, and in no case after solutions have been discussed in class.

    Lateness Policy

    For both labs and problem sets, extracurricular activities and heavy workloads in other classes don't count as "extraordinary", no matter how unexpected or important or time-consuming.

    Nevertheless, everyone gets truly behind from time to time. In recognition of this, you are allowed two late submissions (no more than 4 days late in each case). Please let us know ahead of time that you will be submitting late so we can keep track of things more easily.

    Students must complete all labs and assignments to pass the course.

    Collaboration Policy

    You are encouraged to collaborate on problem sets, but must turn in separate solutions; the names of your collaborators must appear on each submission.

    (This elaboration of the policy on collaboration is paraphrased from COS 126:) You must reach your own understanding of the problem and discover a path to its solution. During this time, discussions with friends are encouraged. However, when the time comes to write down the solution to the problem, such discussions are no longer appropriate -- the solution must be your own work, so you must work on the written assignment on your own. If you have a question, you can certainly ask friends or teaching assistants, but do not, under any circumstances, copy another person's work or present it as your own. This is a violation of academic regulations.

    Examinations

    There may well be short, unannounced, in-class quizzes to verify your existence and test your understanding. These will be worth 5-10 percent of the course grade. Regular class attendance is expected; frequent absences are grounds for a failing grade regardless of other performance.

    A take-home, open-book midterm examination will be given during the week before fall break. It will cover material presented and discussed in class and any relevant reading through Monday, October 17. It will be worth 20 percent of the course grade.

    An open-book final examination will be given during the fall-term exam period. It will cover all of the relevant readings and material presented and discussed in class. It will be worth 35-40 percent of the course grade.

    Sorry: no collaboration on take-home exams or the final.

    Textbook and Readings

    There is no assigned text for this course; I have never found anything that seems right. Fluency with Information Technology by Larry Snyder (Addison-Wesley, 2004) is the closest so far, but it's expensive. Notes and readings will be posted online. The weekly readings are for background, context, general education, and/or entertainment. You are not expected to know any of the detailed content, but you should at least understand the general ideas.

    I have half a dozen books that purport to cover the same kinds of areas as the course. None feels right to me, but among them there is coverage of many class topics, so you might find it helpful to browse in them a bit. Available for loan; drop in to take a look.

    Meanwhile, check out the bibliography for other suggestions.