Letter: This is no bug

Sir: The "Millennium Bug" (Review, 20 August) is not a bug, it is a bomb.

A bug is something that performs erratically, unpredictably or incorrectly, so called because, in computer lore, a program fault in 1944 with the Harvard Mark I was traced to two valve contacts where a moth had got stuck. A short circuit was caused, literally, by a bug.

A bomb is the result of a machine being designed, programmed or built, deliberately or unwittingly, to do something that turns out to be undesirable for the user. The most common bombs are parting gifts from unhappy employees. The year 2000 problem is a bomb. Affected systems were built with 2-digit registers for the year (96, 97, 98, 99, 00) so that when the date gets to 00, the internal clocks more or less reset by 100 years. They are performing, alas, as designed.

It does not lurk deep inside every computer system. The Apple Macintosh has a four-digit year register, and has had since its birth in 1984. If it amuses you, you can set the clock on your Mac to 2010 and whistle a merry tune while you work. Remember to set the clock back before you write any invoices, though. Although your clients would love the 12-year credit, their accounts system would probably crash as soon as the date went in, since they are probably on PCs.

The Millennium Bomb is a feature of older mainframes, cheap embedded chips (such as in cars, VCRs, washing machines, aircraft etc) and some Windows/Intel PCs.

DAVID WHELAN

London SE11