The stack circuitry of the Intel 8087 floating point chip, reverse-engineered

Early microprocessors were very slow when operating with floating-point numbers.
But in 1980, Intel introduced the 8087 floating-point coprocessor, performing
floating-point operations up
to 100 times faster.
This was a huge benefit for IBM PC
applications such as AutoCAD, spreadsheets, and flight simulators.
The 8087 was so effective that today's computers still use a floating-point system based on the 8087.1