6.033 - Computer System Engineering One-page memo #1

Read Medical Devices: The Therac-25 by Leveson (which is an updated version of An Investigation of the Therac-25 Accidents by Leveson and Turner) and the NYTimes article on recent similar problems.

Although there are many cases in which software design and failure has led to the loss of life, the case of the Therac-25 is among the best known and most widely cited because of the depth of analysis that was performed by professor Nancy Leveson and her graduate student Clark Turner. The Leveson paper is quite long, and not all parts are equally important. This is a good opportunity for you to begin practicing how to get the interesting stuff out of a paper without getting bogged down in minor detail:

Now ask yourself why it was assigned as a 6.033 reading, and with that in mind, start working your way through the meat of the paper. Some sections can be skimmed quickly, while other parts require careful study. Not surprisingly, there is also some redundant information that you can ignore.

As you read the paper, try to distinguish solid technical facts from higher-level statements that the authors are trying to make about process, procedures and policy. You might find it useful to note the places where you agree or disagree with the authors' analysis.

Finally, don't be dismayed by unfamiliar technical jargon; make a guess about what it means and move on. The authors may explain it two paragraphs later, or two pages later, or perhaps never get around to it. There is a good chance that you will discover that it didn't actually matter. But if it does, you have something to ask about in recitation.

After reading the Leveson paper, write a one-page memo:

The FDA is wondering whether new regulations could help prevent future accidents with medical radiation devices such as occured with the Therac-25. They've hired you to help them. They want you to recommend which of the following areas would most benefit from new regulations: You should outline a specific new regulation in one of these areas and argue why it would significantly reduce the probability of future accidents. You do not need to state your regulation in legal prose; clear, professional language is important, however.

Pay specific attention to how your recommendations may have helped prevent the recent problems described in the NYTimes article.

Remember, use no more than one sheet of paper for your memo. For formatting specifications, consult the guidelines for writing a memo and the Mayfield Handbook. Please be concise. You will not be able to address every issue in one page, so you will have to make your best argument and judiciously choose supporting facts.

You may find it useful to consult a sample memo to see what a memo should look like.

You will turn in two versions of this memo. The first version is due in recitation when you will discuss the Therac-25. Please submit it at the course submissions page. You will discuss the technical aspects of the Therac-25 in that recitation, and you will discuss the writing aspects of how to organize a good memo in the following Friday writing program section. Then, you will turn in a second, revised version. Check the schedule page for the exact dates.


Your submissions will be graded by both the 6.033 staff and the Writing Program, as described here. The staff grade will focus on your identification of failed analyses, your suggestion of reasonable methods to address these failures, and on how well you articulate your argument. The Writing Program grade will focus on the style and clarity of your memo, according to the following key areas:
  1. Completeness of Ideas. Does the memo present the information necessary for the reader to understand the new regulation and why it is needed? Does the memo make a clear, unified argument? Does it provide supporting evidence from the article, with appropriate credit?
  2. Organization and Sequencing. Is the memo's organization clear and logical? Does it order the information in a way that is easy to understand? Does each paragraph have an effective topic sentence?
  3. Language & Syntax. Are the memo's spelling and grammar correct?
  4. Format and Visual Organization. Does the assignment adhere to standard memo format and conventions? Does it use segmentation, white space, and other visual characteristics to aid clarity?

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