An interesting detail about the Intel 8087 floating point processor (FPU) is that it’s a co-processor that shares a bus with the 8086 or 8088 CPU and system memory, which means that somehow both the CPU and FPU need to know which instructions are intended for the FPU. Key to this are eight so-called ESCAPE […]
Continuing his reverse-engineering of the Intel 8087, [Ken Shirriff] covers the conditional tests that are implemented in the microcode of this floating point processing unit (FPU). This microcode contains the details on how to perform the many types of specialized instructions, like cos and arctan, all of which decode into many microcode ops. These micro […]
Although something that’s taken for granted these days, the ability to perform floating-point operations in hardware was, for the longest time, something reserved for people with big wallets. This began to change around the time that Intel released the 8087 FPU coprocessor in 1980, featuring hardware support for floating-point arithmetic at a blistering 50 KFLOPS. […]
[Michael Wessel] found some of his old DOS 3D graphics software and tried to run it on an 8088 PC. The tale of adding an 8087 co-processor to speed up the rendering was anything but straightforward, resulting in a useful little project. There was a point around the end of the 1980s when the world […]