Ken Shirriff opened up Intel’s 8087, a chip from 1980, to study a seemingly simple instruction: multiply a number by a power of two. The basic operation is just adjusting an exponent. But handling rounding, infinities and other edge cases brings the implementation to over 140 micro-instructions. His reverse engineering also uncovered a feature Intel never documented for the chip: a flag telling software whether a result was rounded up or down. https://news.ycombinator.com/item?id=496…