CSC 205
Professor Stearns
Unusual Requirements

This list of unusual requirements provides good material for a system boundary lecture and software design discussion. These are all actual cases that, in some way, had a profound effect on Dan's life.

• The 8 day week
  Dan had a customer that was quite proud of their 8 day week because it solved the week/month problem. For this customer, each month has exactly 4 weeks. Each week contains either 7 or 8 days; for example January has weeks containing 7,8,8,8 days. September has weeks containing 7,8,7,8 days. This customer requires that their software vendor handle 8 day weeks.

• Grenade requirement
  A digital telephone exchange customer requires their systems to survive a grenade explosion in the [geometric] center of the system. Question: how would you test such a feature?

• Optimize
  A city in California specified a requirement to "optimize the efficiency" of one of their computer systems. Unfortunately, this requirement isn't all that unusual. Wait until you hear the result!

• Sort Order
  A telephone company specified that the phonebook listings have an unusual sort order. All the Macs (Mac, MC, Mc) were required to be grouped; the normal sort order doesn't do this.

• Made in the U.S.A
  A customer specified that all components of a large embedded system be "Made in the U.S.A".

• We can't read
  A customer, who had many functionally illiterate employees, required a large application with no displayed text. This requirement was stipulated only after a previous system, with much displayed text, had failed badly.

• Solve this one!
  A company ordered an embedded software system (ROMs, no disk) to be installed in several countries using a variety of languages. Two requirements made for quite a difficult design problem (but they were insistent):
  
  1. The binaries must be identical across all installations. (you can't fault them for this requirement)
  2. The software may not ask the users their language choice. (a reasonable requirement)

• "Perfect" testing
  A customer, obviously weary of software defects, requested that a large software system be 100% path tested. (i.e. The test cases must exercise every possible path through the software).

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  Last updated on 10/13/98