The Pentium processor was Intel’s top-of-the-line release in 1993. Shortly after, a bug was discovered in the Pentium’s floating-point division algorithm by Professor Nicely, leading to massive media attention and a recall. Despite initial attempts by Intel to downplay the issue, public outcry and media coverage forced Intel to replace the faulty Pentium chips. The bug was caused by missing entries in the Pentium’s division lookup table due to a mathematical error, ultimately leading to a $475 million recall. The bug, known as the FDIV bug, highlighted the complexities of floating-point arithmetic and the intricacies of hardware implementation. Intel engineers and mathematicians studied the bug, ultimately reverse-engineering the division algorithm to understand its flaws. The Pentium’s division algorithm used a base-4 SRT approach, which was faster but required more complex hardware, including a programmable logic array (PLA) to store the lookup table. Intel used sophisticated techniques to generate compact PLAs to fix the bug.
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