Extracting ROM constants from the 8087 math coprocessor's die
I opened up an 8087 chip and took photos with a microscope. The photo below shows the chip’s tiny silicon die. Around the edges of the chip, tiny bond wires connect the chip to the 40 external pins. The labels show the main functional blocks, based on my reverse engineering. By examining the chip closely, various constants can be read out of the chip’s ROM, numbers such as pi that the chip uses in its calculations.