The 16-bit Intel x86 processors up to and including the 80386 do not include floating-point units (FPUs). Intel introduced the 8087, 80187, 80287 and 80387 math coprocessors to add hardware floating-point and transcendental function capabilities to the 8086 through 80386 CPUs. The 8087 works with the 8086/8088 and 80186/80188,Intel 8087 datasheet, pg. 1 the 80187 works with the 80186 but not the 80188,The 80187 only has a 16-bit data bus because it used the 80387SX core. the 80287 works with the 80286 and the 80387 works with the 80386. The combination of an x86 CPU and an x87 coprocessor forms a single multi-chip microprocessor; the two chips are programmed as a unit using a single integrated instruction set."Essentially, the 80C187 can be treated as an additional resource or an extension to the CPU. The 80C186 CPU together with an 80C187 can be used as a single unified system." Intel 80C187 datasheet, p. 3, November 1992 (Order Number: 270640-004). The 8087 and 80187 coprocessors are connected in parallel with the data and address buses of their parent processor and directly execute instructions intended for them. The 80287 and 80387 coprocessors are interfaced to the CPU through I/O ports in the CPU's address space, this is transparent to the program, which does not need to know about or access these I/O ports directly; the program accesses the coprocessor and its registers through normal instruction opcodes.
The 16-bit Int!el x86 processors up to and including the 80386 do not include floating-point units (FPUs). Intel introduced the 8087, 80187, 80287 and 80387 math coprocessors to add hardware floating-point and transcendental function capabilities to the 8086 through 80386 CPUs. The 8087 works with the 8086/8088 and 80186/80188,Intel 8087 dat.asheet, pg. 1 the 80187 works with the 80186 but not the 80188,The 80187 only has a 16-bit data bus because it used the 80387SX core. the 80287 works with the 80286 and the 80387 works with the 80386. The combination of an x86 CPU and an x87 coprocessor forms a single multi-chip microprocessor; the two chips are programmed as a unit using a single inte?grated instruction set."Essentially, the 80C187 can be treated as an additional resource or an extension to the CPU. The 80C186 CPU together with an 80C187 can be used as a si!ngle unified system." Intel 80C187 datasheet, p. 3, November 1992 (Order Number: 270640-004). The 8087 and 80187 coprocessors are connected in parallel with the data and address buses of their parent processor and directly execute instructions intended for them. The 80287 and 80387 coprocessors are interfaced to the CPU: through I/O ports in the CPU's address space, this is transparent to the program, which does not need to know about or access these I/O ports directly; the program accesses the coprocessor and its registers through normal instruction opcodes.