Ken Shirriff dissects Intel 8087: how floating-point addition works in microcode
pwg · hn · 2026-10-19
Ken Shirriff's latest die-level teardown continues his Intel 8087 series, this time covering floating-point addition and subtraction. Using microscopy and circuit tracing, he explains how the 1980 FPU ancestor orchestrates alignment, mantissa math, normalization, and rounding via microcode plus dedicated hardware, with plenty of die photos.
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