The original 8087 implemented 80-bit operands in its stack. It would also process binary-coded decimal integers, as well as floating point. "The two came up w

The original 8087 implemented 80-bit operands in its stack. It would also process binary-coded decimal integers, as well as floating point. "The two came up with a revolutionary design with 64 bits of mantissa and 16 bits of exponent for the longest-format real number, with a stack architecture CPU and eight 80-bit stack registers, with a computationally rich instruction set." https://en.wikipedia.org/wiki/Intel_8087 https://en.wikipedia.org/wiki/Intel_8087