Intel 8087

  • Intel
  • AMD
  • NEC
  • Siemens AG
  • Mitsubishi

The Intel 8087 is an in NMOS technology ( HMOS III, 3 microns ) floating point unit produced (English floating point unit, FPU short ). Intel developed the 8087 in 1980 as x87 coprocessor for 8086, 8088, 80186 and 80188 processors.

Properties and Uses

The 8087 is the first designed by Intel floating point unit for 16- bit processors. He offloads the main processor for calculations with floating point numbers. Without coprocessor solve floating point instructions from a CPU Exception that can be used by the operating system to perform the calculations on a software emulation running on the main processor. Calculations with use of the 8087 are 75 - to 100 - times faster than emulated coprocessor. The 8087 can perform about 50,000 FLOP per second and contains 45,000 transistors. This FPU supports clock frequencies of 5 ( 8087 ), 8 ( 8087-2 ) or 10 MHz ( 8087-1 ).

On the motherboard of the IBM PC, a slot was free, in the 8087 could be easily retrofitted. Because the operating system MS- DOS gave no such emulation available, it was the object of the application programs to bring such an emulation when they used floating-point calculations and should also run on systems without FPU without modification. Many then used programming languages ​​brought with corresponding emulation libraries. There were, however, FPU emulators that could be loaded as a device driver or TSR and then were all application programs.

The 8087 was replaced by the 80287, I387 and I487 the. Since i486DX the Intel processors have an integrated floating point unit.

The 8087 could also be used in the Bridge Boards for the Amiga.

15611
de