The Pentium Processor’s Innovative (and Complicated) Method of Multiplying by Three, Fast
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Summary
Intel’s now relatively ancient Pentium processor from 1993 had a particularly complex circuit for speeding up the performance of a specific mathematical operation.
The operation in question was multiplying a number by three, and it turned out that this was an incredibly efficient piece of circuitry that enabled the Pentium to perform this task far faster than competing products.
The reason for this complexity was the mathematical optimization techniques used by the processor for number multiplication, which ultimately meant that multiplying a value by three was not straightforward.
This required a specialized, and very large, circuit just for this operation alone.
The discovery of this feature has given Intel engineers of the era a well-deserved pat on the back for their innovative solution, found within the Floating Point Unit (FPU).
