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The U.S. Navy has posted a Web page written in either techie or bureaucratese (I can't be sure) in which it says (approximately) that its Global Positioning System (GPS) guidance satellites, used by people who want to know exactly where they are, and by missiles that should also know exactly where they are, will not be working as planned as of August 22, 1999. Sorry about that! The Navy's advice: "Call your vendor."
Anyone who thinks that the government plans carefully and would never allow a snafu like this had better think again. What the Navy now admits will happen to its GPS system should be magnified a hundred-fold to begin to estimate the confusion that will be caused by the Millennium Bug. Maybe a thousand-fold.
Consider this: the GPS sets the standards for the world's clocks. This affects the banks' interest rate computations.
I am including a detailed analysis of the effects of the GPS rollover. The following document was posted on the Risks-Forum Digest discussion group on March 27, 1997. It says, in short, that there will be extremely serious consequences, beginning in late August, 1999.
At the end of this posting, there is a link to the Navy's GPS page, where the announcement of the coming failure is posted.
But first, read the analysis. It is technical, and it is scary.
One note: "prom" is not a dance. It is "programmable read-only memory." This is that part of a computer's memory that is permanent until a new chip with a new prom is installed. You don't change it by re-writing software external to the chip.
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Date: Thu, 27 Mar 1997 11:10:33 -0700 From: "Jack K. Horner 120775" Subject: Re: Risks Associated with the Year 2000 Problem
The problem is potentially much messier than just the occurrences of the literal value "19" in date types. ANYTHING in software that merely acts as if the first two digits of the date are "19" will have insidious effects.
About a year ago, I worked on an analysis of the Global Positioning System (GPS) ground station code to try to characterize the Y2K problem. We found no less than ten types of manifestations of the problem in a survey of a randomly selected sample of 10% of the code. The occurrence of the literal value "19" was only one of these ten types. Other types included type overflow problems at various dates throughout 1999, Y2K arithmetic that implicitly assumed no dates later than 31 Dec 99 were possible, and implicit module-interface date-type conversions. These problems are potentially infinite in their variety, and not all can be detected with tools. Furthermore, in GPS it is not possible to construct good test cases to see what will happen at the millennium start, because the future (time-) states of the system depend on physical values (orbital elements, pole wander, Jovian gravitational force) that can be determined with sufficient accuracy only from the actual operation of the system within about three months of the time of interest. Approximately 1% of the total GPS code is affected by this class of problems, or affected it.
The GPS user-equipment code is in even deeper trouble because of the Y2K problem, and the breakage will occur well before Jan 1, 2000. Date, in the GPS signal standard, uses exactly thirteen bits (these bits represent a time-unit offset from a conventional epoch date). This allocation is burned into proms on all existing GPS user equipment. On about August 20, 1999, the actual date value will overflow this 13-bit type, and the equipment will fail to produce correct time or position information. Best estimate is that there are ~10^6 [10,000,000] pieces of user equipment that will be immediately affected. Everybody who depends indirectly on those pieces of equipment (meaning all the rest of us) will also be affected. The GPS standards committee is desperately trying to figure out what to do with the problem.
Various well-calibrated software estimation models (SLAM, REVIC, PRICE-S) predict that fixing the Y2K problem in systems of about 500,000 lines of code or larger will take more time than is available between now and the year 2000, regardless of how many programmers are thrown at the job. Most of the US's military command-and-control systems contain more than 500,000 lines of code.
GPS is now the primary means of distributing time standards throughout the US, and throughout much of the world. (The accuracy of the atomic clocks on board the GPS satellites is second only to those maintained by the primary standards clocks in Washington.) Thousands of large financial computers ultimately take their time calibration from GPS, every day. Interest on overnight multi-billion-dollar short-term electronic-funds transactions is computed at millisecond granularity, derived from the GPS standard.
Place your bets.
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