page_title: X87
section_title: 80187
hierarchical_section_title: X87 / Architectural generations / 80187
caption_attribution_description: English: FPU Intel 80C187
context_page_description: x87 is a floating-point-related subset of the x86 architecture instruction set. It originated as an extension of the 8086 instruction set in the form of optional floating-point coprocessors that worked in tandem with corresponding x86 CPUs. These microchips had names ending in "87". This was also known as the NPX. Like other extensions to the basic instruction set, x87 instructions are not strictly needed to construct working programs, but provide hardware and microcode implementations of common numerical tasks, allowing these tasks to be performed much faster than corresponding machine code routines can. The x87 instruction set includes instructions for basic floating-point operations such as addition, subtraction and comparison, but also for more complex numerical operations, such as the computation of the tangent function and its inverse, for example.
  Most x86 processors since the Intel 80486 have had these x87 instructions implemented in the main CPU, but the term is sometimes still used to refer to that part of the instruction set.
context_section_description: The 80187 (80C187) is the math coprocessor for the Intel 80186 CPU. It is incapable of operating with the 80188, as the 80188 has an 8-bit data bus; the 80188 can only use the 8087. The 80187 did not appear at the same time as the 80186 and 80188, but was in fact launched after the 80287 and the 80387. Although the interface to the main processor is the same as that of the 8087, its core is that of the 80387 and is thus fully IEEE 754-compliant and capable of executing all the 80387's extra instructions.
caption: 16 MHz version of the Intel 80187
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