Going On A Tangent With The Intel 8087’s Hybrid CORDIC Algorithm

Going On A Tangent With The Intel 8087’s Hybrid CORDIC Algorithm

Continuing their reverse-engineering of Intel’s 8087 FPU, [Ken Shirriff] and friends took a look at one of the trigonometric functions, specifically FPTAN.  The most exciting part with such reverse-engineering is …

Reverse-engineering the vintage Intel 8087’s tangent algorithm: more than CORDIC

Ken Shirriff has published another teardown of Intel’s 8087 floating-point coprocessor on righto.com, this time covering the FPTAN tangent instruction. He removed the chip’s lid with a chisel and imaged the die under a microscope, then read the 1648 micro-instructions in the microcode ROM to work out the algorithm. The 8087 computes a tangent in […]

Reverse-engineering the vintage Intel 8087's tangent algorithm: more than CORDIC

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