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.

Almach (stars.astro.illinois.edu) ALMACH (Gamma Andromedae). You take your new telescope to the back yard perhaps wondering what to examine. When finished with the Moon and the bright planets you turn to the stars, first perhaps to the grand Orion Nebula, next maybe to the magnificent Andromeda Galaxy. Then it is time for double stars. The sky abounds with them, northern winter’s Castor, springtime’s Mizar and Alcor, summer’s Albireo (the seasons reversed for the southern hemisphere), dozens of others easily found. Among the best of all, however, is the last star of the string of bright beauties that helps make the constellation Andromeda, second magnitude (2.16) Almach, Andromeda’s Gamma star.

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.