80x87 Floating Point Units

© Intel, Photo by HARDWARECOP
© Intel, Photo by HARDWARECOP

80x87 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". 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. Before x87 instructions were standard in PCs, compilers or programmers had to use rather slow library calls to perform floating-point operations, a method that is still common in (low-cost) embedded systems.

 

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8087 Class


The Intel 8087, announced in 1980, was the first x87 floating-point coprocessor for the 8086 line of microprocessors.

Intel D8087
Intel D8087

Intel C8087-2

Intel C8087-2 Front View
Intel C8087-2 Back View
Intel C8087-2 Side View

C8087-2
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Intel D8087

Intel D8087 Front View
Intel D8087 Back View
Intel D8087 Side View

Kindly donated by Pauli Rautakorpi.

D8087
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Intel D8087-1

Intel D8087-1 Front View
Intel D8087-1 Back View
Intel D8087 Side View

D8087-1
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80287 Class


The 80287 (i287) was the math coprocessor for the Intel 80286 series of microprocessors. Intel's models included variants with specified upper frequency limits ranging from 6 up to 12 MHz. Later followed the i80287XL with 387 microarchitecture and the i80287XLT, a special version intended for laptops, as well as other variants.

IIT 2C87-12
IIT 2C87-12
Intel C80287-3
Intel C80287-3
Intel D80287-8
Intel D80287-8

IIT 2C87-12

IIT 2C87-12 Front View
IIT 2C87-12 Back View
IIT 2C87-12 Side View

Kindly donated by Pauli Rautakorpi.

2C87-12
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Intel C80287-3

Intel C80287-3 Front View
Intel C80287-3 Back View
Intel C80287-3 Side View

Kindly donated by Pauli Rautakorpi.

 

C80287-3
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Intel D80287-8

Intel D80287-8 Front View
Intel D80287-8 Back View
Intel D80287-8 Side View

Kindly donated by Pauli Rautakorpi.

D80287-8
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Intel D80287-10

Intel D80287-10 Front View
Intel D80287-10 Back View
Intel D80287-10 Side View

D80287-10
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Intel C80287XL

Intel C80287XL Front View
Intel C80287XL Back View
Intel C80287XL Side View
Intel i287XL User's Guide

C80287XL
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80387 Class


The 80387 (387 or i387) was the first Intel coprocessor to be fully compliant with the IEEE 754 standard. Released in 1987, a full two years after the 386 chip, the i387 included much improved speed over Intel's previous 8087/80287 coprocessors, and improved the characteristics of trigonometric functions. (The 80287 limited the argument range to plus or minus 45 degrees.)

Cyrix FasMath CX-83D87-33-GP

Cyrix FasMath 33GP (the exact FPU!!) Die Picture by Pauli Rautakorpi - Published under the Creative Commons Attribution 3.0 Unported license. Slightly edited by HARDWARECOP.

CX-83D87-33-GP
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IIT 3C87-33


3C87-33
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IIT 3C87-40

3C87-40
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Intel 80387 16 MHz

A80387-16
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Intel 80387 20 MHz


A80387-20
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Intel 80387 DX 16-33

Intel 80387 Die Picture by Pauli Rautakorpi - Published under the Creative Commons Attribution 3.0 Unported license. Slightly edited by HARDWARECOP.

A80387DX 16-33
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Intel RapidCad-2

RAPIDCAD-2
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ULSI US83C87-C 40


US83C87-C 40
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