The Problem

Today's processors may be the most complex machines ever designed by man. When dealing with such a level of complexity, it's impossible to avoid errors. In other words, every complex processor is shipped with bugs—some known, some not.

When the first version of a processor is shipped, that is referred to as the first stepping, or revision, of the silicon. As time goes on and bugs are uncovered, the manufacturer redesigns the silicon to eliminate the problems recognized at the time. This comprises the next stepping of the silicon. During the life of a processor, it typically passes through a number of steppings as improvements/fixes are included in the design.

If a machine is purchased with an earlier stepping of the processor and it is later decided to update to a later stepping (to eliminate problems or, possibly, to improve performance), the user would have to purchase a new processor—an expensive proposition.