← Tuesday, September 29, 2026Performance & OSDeep dive
Intel 8087 combined CORDIC and polynomial methods for fast tangent
Reverse-engineering the 8087 reveals that its tangent instruction combined CORDIC with polynomial approximation, computing tangent in 90 microseconds versus 13,000 on the 8086. It is a detailed example of how algorithm and hardware choices shape performance.
- What
- The Intel 8087’s FPTAN instruction combined CORDIC with a polynomial approximation to compute tangent.
- How
- Reverse-engineering the chip’s circuitry and microcode revealed a combination intended to deliver both high accuracy and performance.
- Why it matters
- The design shows how combining algorithms and specialized hardware can accelerate numerical functions.
Read on righto.com → Hacker News · 11 comments
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