Hoylen's Weblog

Fri, 28 May 2010

Newton's Y2K10 problem

The Apple iPad was released in Australia (as well as many other countries) today, but it is interesting to remember its ancestor--the Apple Newton. The Apple Newton was the original device that created the term Personal Digital Assistant (PDA), and many of the concepts in the iPad were already present in the Newton.

The Newton had its own date problem. The Apple Newton represented integers as signed 30-bit numbers. The processor does use 32-bit words Like nearly all modern microprocessors do, but the Newton uses two bits from it for its own housekeeping. The clock on the Newton represents time as the number of seconds past 1 January 1993 as an integer. Since the maximum integer is 2^29, the maximum time the Newton could represent is 2010-01-05 18:48:31.

It is an interesting coincidence that the iPad was released in the same year that the Newton's clock ends. The iPad was announced on 27 January 2010, just 22 days after the Newton's clock reached its end. However, enterprising Newton programmers have created hacks to extend the Newton's clock.

The Apple Newton was a very innovative platform, with a unique and powerful object-oriented data model. Have a look at the Newton's technical documentation to see how it worked and why they deliberately made integers 30-bits long.