Intel 8087
Intel 8087 Math Coprocessor
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| Produced | 1980 |
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| Marketed by | Intel, IBM |
| Designed by | Intel |
| Common manufacturer(s) | |
| Max. CPU clock rate | 4 MHz to 10 MHz |
| Min. feature size | 3 μm |
| Instruction set | x87 (coprocessor extension of x86-16) |
| Predecessor | 8231 |
| Successor | 80287 |
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The Intel 8087, announced in 1980, was the first x87 floating-point coprocessor for the 8086 line of microprocessors.
The purpose of the 8087 was to speed up computations for floating-point arithmetic, such as addition, subtraction, multiplication, division, and square root. It also computed transcendental functions such as exponential, logarithmic or trigonometric calculations, and besides floating-point it could also operate on large binary and decimal integers. The performance enhancements were from approximately 20% to over 500%, depending on the specific application. The 8087 could perform about 50,000 FLOPS using around 2.4 watts. Only arithmetic operations benefited from installation of an 8087; computers used only with such applications as word processing, for example, would not benefit from the extra expense (around $150) and power consumption of an 8087.
The 8087 was an advanced IC for its time, pushing the limits of period manufacturing technology. Initial yields were extremely low.
The sales of the 8087 received a significant boost when IBM included a coprocessor socket on the IBM PC motherboard. Due to a shortage of chips, IBM did not actually offer the 8087 as an option for the PC until it had been on the market for six months. Development of the 8087 led to the IEEE 754-1985 standard for floating-point arithmetic. There were later x87 coprocessors for the 80186 (not used in PC-compatibles), 80286, 80386, and 80386SX processors. Starting with the 80486, the later Intel x86 processors did not use a separate floating point coprocessor; floating point functions were provided integrated with the processor.
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