• Class 24: Garbage Collection [PPTX] [PDF]
• Class 25: Software Disasters! [PPTX] [PDF]

The Exam 2 template is here: exam2.docx.

• Class 22: Graphical User Interfaces [PPTX] [PDF]
• Class 23: Network Programming [PPTX] [PDF]

• Class 20: Verifying Bytecodes [PPTX] [PDF]
• Class 21: Hair-Dryer Attacks [PPTX] [PDF]

This is the paper I talked about in class today:

Sudhakar Govindavajhala and Andrew W. Appel, Using Memory Errors to Attack a Virtual Machine, IEEE Symposium on Security and Privacy (Oakland), 2003. [PDF"]

I think you should be able to understand almost everything in the paper from what we have done in class. Sudhakar also has some discussion about questions about the paper on his website: http://www.cs.princeton.edu/~sudhakar/papers/memerr-slashdot-commentary.html. It has better answers to some of the physics questions than I was able to give in class.

If you’re curious how much you should be worried about memory bit errors normally, you may be interested in this paper which analyzes the bit errors on Google’s servers over a 2.5 year period: DRAM Errors in the Wild: A Large-Scale Field Study by Bianca Schroeder, Eduardo Pinheiro, and Wolf-Dietrich Weber, SIGMETRICS 2009. (Short answer: if you don’t have as many machines as Google, you shouldn’t lose too much sleep over this.)

• Class 18: Concurrency (wait and notify, Priority, Mars) [PDF] [PPTX]
• Class 19: Java Security (safe programming languages, Java byte codes, verification) [PDF] [PPTX]

• Class 16: [PDF] [PPTX]
• Class 17: [PDF] [PPTX]

Since I didn’t have time to discussion slide 29 from Class 17 (“Problems in Simula that motivated CLU”) in class, you should expect to have a question on Exam 2 that is based on this slide.

Substitution principle example: [PDF]

I will also clarify the “Social Network” movie challenge question I mentioned at the beginning of class today. There are at least three scenes in the movie that have some technical computing content:

• The scene where Mark describes the algorithms used to acquire the pictures for “Facemash” and the ELO-based ranking algorithm they use.
• The scene where Mark walks out of Matt Welsh’s Operating Systems course, answering a question on the way out.
• The scene where Mark “interviews” candidates for internships.

The second one of these suggests the most obvious challenge question: explain the question and answer Mark gives, and what assumptions not visible in the scene are necessary for Mark’s answer to be correct. This definitely involves topics not covered in cs2220, so would require some outside learning about operating systems. (For Matt Welsh’s take of Mark Zuckerberg’s performance in his course, see How I almost killed Facebook from his blog.)

The other two suggest less obvious challenge questions (especially the third one, and I don’t want to encourage any programming under the influence!), and Aaron Sorkin’s dialogue in the movie moves really quickly, so for these you would have to both define and answer your own interesting challenge question.

There are a lot of inaccuracies and distortions in the movie, but its also a lot of fun and very well done.