Editor's Notes
http://www.y2ktimebomb.com/
That’s one of the sites where you can read about a major problem we residents of Earth will face as we celebrate the rolling over of the digits after 23:59:59 on December 31, 1999. The problem is that in many cases there aren’t enough digits to roll over. Unless something is done about it, many machines and programs will tell you that your age is suddenly ­(100­y), where y is the number of years you’ve actually lived. If you’re 105, you may get a computer letter calling on you to register for kindergarten.

Most of you have probably read about the inability of many computer programs to distinguish between the years 1900 and 2000, because the year is expressed by only 2 digits. Thus, the year after 1999 of the common era (i.e., year 99 anno moduli­ AM) becomes 1900 (i.e., year 00 AM), neatly compressing time into a never-ending series of identical centuries. No doubt you’ve also read about the many real problems it will cause, the catastrophic expense involved in fixing whatever portion of it can be found and fixed, the general indifference to the problem, and the shortness of time and paucity of personnel available to work on it.

Where did it all start? Probably back in the first quarter of this century when Hollerith’s punched cards (first used more than 100 years ago) started to become widely used for storing sortable data. With only 80 characters available, reducing the year to two characters seemed like a worthwhile tradeoff to obtain two additional characters for important data. Remember, this was a time when nearly all printed forms, such as bank checks, had a date line 19__ (they still do!?), since it was likely to be valid throughout one’s lifetime (or at least, one’s watch interval). Scarcely a thought was given to the next century.

It’s interesting to speculate on the role played in the origins of this problem by the fact that the twentieth century is a pre-millenial century, i.e., that to fairly take into account dates far into the future, all four digits have to be allowed to roll over. What if this were a century somewhere in the middle (say, the sixteenth or forty-third)? Then for many, many generations, the maximum century rollover would be a single digit. It’s conceivable that more software designers would be willing to take the long view when only a single digit had to be advanced at some distant time within the next 99 years.

Much of the discussion in the popular press has to do with the more-obvious implications, relating to billing and inventory, tax and interest computations, demographics. There are also problems in routines related to safety, such as inspection intervals. While many unfixed problems will show up simultaneously, many more, lying dormant, will show up sporadically, or even by the absence of some important event. Faulty computer programs may lie embedded in microcomputers and microcontrollers in transportation, medical, military, and environmental equipment, perhaps designed by engineers now retired, and manufactured by companies no longer in existence.

It’s a hairy problem, one that it behooves us to learn more about. A good place to start is at the above Web address, which is co-sponsored by Peter de Jager, probably the leading consultant on the problem.

Dan.Sheingold@analog.com

THE AUTHORS
 David Skolnick is a Technical Writer with ADI’s Computer Products Division, Norwood, MA, where he writes and illustrates manuals and data sheets and has written or edited a number of DSP application notes. He holds a Bachelor degree in Electrical Engineering Technology and is completing a Master of Technical and Professional Writing program at Northeastern U. He enjoys gardening, outdoor sports, and anything to do with his kids. Noam Levine is a Product Manager in the 16-bit DSP product line, working on new-product definitions and fixed-point DSP applications. He holds a BSEE from Boston University and an MSEE in DSP from Northeastern University. He has authored several application notes, technical articles, and conference papers. When not in the digital domain, Noam can be found playing jazz saxophone and working on his SCCA competition driving license. Mike Byrne is Applications Manager with the Applications Group in Limerick, Ireland. The group provides customer design-in support and are involved with new-product definitions. He holds a BSc. in electronic systems from the University of Limerick. A patent-holder, he is the author of several application notes and technical articles. His leisure-time activities include music and outdoor sports. Ken Kavanagh is a Technician with the Applications Group in Limerick, Ireland, where he provides customer support and is involved with the design of evaluation boards and support software. He holds a Diploma in Electronics and is currently undertaking a part-time degree course in the University of Limerick. His leisure-time activities include music, tennis, and badminton. Jim Ryan is a Senior Engineer with the Applications Group in Limerick, Ireland, where he provides customer support and is involved with new-product definition for CMOS converter products. He holds a BSc. in Electronic Systems and an MEng. in Computer Systems, both from the University of Limerick, and has worked previously as a designer of laboratory instrumentation. In his leisure time he enjoys rugby and hill-walking. Albert O’Grady is a member of the Applications Group at Analog Devices, in Limerick Ireland, in support of both analog-to-digital and digital-to-analog converter products. He holds a BEng. from the University of Limerick. In his spare time, Albert enjoys reading and plays badminton and tennis.
Dave Robertson is a design engineer in the Analog Devices High-Speed Converter group in Wilmington, MA. His photo and a brief biography appeared in Analog Dialogue 30-3.

Steve Guinta is the Technical Training Manager for ADI’s Central Applications Group in Wilmington, MA. His photo and a brief biography appeared in Analog Dialogue 30-2.