Ken Shirriff @righto.com · Jun 13

Intel introduced the 8087 floating-point chip in 1980 to make math faster. The chip does tangents, square roots, and so forth, but fundamentally everything is computed through additions and subtractions, performed by an adder at the heart of the chip. Let's look at the adder's circuitry... 1/N

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Ken Shirriff · Jun 13

For performance, the adder is constructed in blocks of four bits. Here's one block under the microscope. This shows the chip's single metal layer, the metal wiring on top of the silicon that connects things. Modern chips can have over 20 layers. The thick vertical wire on the side power the adder.

@wixora.bsky.social · Jun 13

I always suspected there was a small abacus in there. Thanks for pointing that out.

Flemming Gram · Jun 13

Can anyone recommend a text on the algorithms? I am curious how eg. sqrt is done.