Intel 8087

bias generation circuit

Inside the die of Intel’s 8087 coprocessor chip, root of modern floating point (righto.com) Looking inside the Intel 8087, an early floating point chip, I noticed an interesting feature on the die: the substrate bias generation circuit. In this article I explain how this circuit is implemented, using analog and digital circuitry to create a negative voltage.

John Thune (Wikipedia) John Randolph Thune (/ˈθuːn/ THOON; born January 7, 1961) is an American politician serving as the senior United States senator from South Dakota, a seat he has held since 2005. A member of the Republican Party, he will become the Senate majority leader and Senate Republican leader in January 2025. Thune is in his fourth Senate term and is the Senate minority whip, a post he has held since 2021, and is the dean of South Dakota’s congressional delegation. He served three terms as the U.S. representative for South Dakota’s at-large congressional district from 1997 to 2003.

Extracting ROM constants from the 8087 math coprocessor’s die (righto.com) Intel introduced the 8087 chip in 1980 to improve floating-point performance on the 8086 and 8088 processors, and it was used with the original IBM PC. Since early microprocessors operated only on integers, arithmetic with floating-point numbers was slow and transcendental operations such as arctangent or logarithms were even worse. Adding the 8087 co-processor chip to a system made floating-point operations up to 100 times faster.