- The adder at the heart of Intel’s 8087 floating-point chip (righto.com)
In 1980, Intel released the Intel 8087 floating-point coprocessor, a chip that could make math up to 100 times faster. As well as arithmetic and square roots, the 8087 computed transcendental functions including tangent, exponentiation, and logarithms. But it all depended on a 69-bit adder: “The arithmetic heart of the floating-point execution unit is centered about a nanomachine comprised of the adder and its related registers, shifters and control circuitry,” as the patent describes it. In this article, I explain the circuitry of this adder.
- Die analysis of the 8087 math coprocessor’s fast bit shifter (righto.com)
Floating-point numbers are very useful for scientific programming, but early microprocessors only supported integers directly. Although floating-point was common in mainframes back in the 1950s and 1960s, it wasn’t until 1980 that Intel introduced the 8087 floating-point coprocessor for microcomputers. Adding this chip to a microcomputer such as the IBM PC made floating-point operations up to 100 times faster. This was a huge benefit for applications such as AutoCAD, spreadsheets, or flight simulators. The downside was the 8087 chip cost hundreds of dollars.
- Conditions in the Intel 8087 floating-point chip’s microcode (righto.com)
In the 1980s, if you wanted your computer to do floating-point calculations faster, you could buy the Intel 8087 floating-point coprocessor chip. Plugging it into your IBM PC would make operations up to 100 times faster, a big boost for spreadsheets and other number-crunching applications. The 8087 uses complicated algorithms to compute trigonometric, logarithmic, and exponential functions. These algorithms are implemented inside the chip in microcode. I’m part of a group that is reverse-engineering this microcode. In this post, I examine the 49 types of conditional tests that the 8087’s microcode uses inside its algorithms. Some conditions are simple, such as checking if a number is zero or negative, while others are specialized, such as determining what direction to round a number.
- Instruction decoding in the Intel 8087 floating-point chip (righto.com)
In the 1980s, if you wanted your IBM PC to run faster, you could buy the Intel 8087 floating-point coprocessor chip. With this chip, CAD software, spreadsheets, flight simulators, and other programs were much speedier. The 8087 chip could add, subtract, multiply, and divide, of course, but it could also compute transcendental functions such as tangent and logarithms, as well as provide constants such as π. In total, the 8087 added 62 new instructions to the computer.
- Windows 95 (Wikipedia)
Windows 95 is a consumer-oriented operating system developed by Microsoft as part of its Windows 9x family of operating systems. The first operating system in the 9x family, it is the successor to Windows 3.1, and was released to manufacturing on July 14, 1995, and generally to retail on August 24, 1995, almost three months after the release of Windows NT 3.51. Windows 95 is the first version of Microsoft Windows to include the Modern Windows Feel (Taskbar, Start Menu.) Windows 95 merged Microsoft’s formerly separate MS-DOS and Microsoft Windows products, and featured significant improvements over its predecessor, most notably in the graphical user interface (GUI) and in its simplified “plug-and-play” features. There were also major changes made to the core components of the operating system, such as moving from a mainly cooperatively multitasked 16-bit architecture to a 32-bit preemptive multitasking architecture, at least when running only 32-bit protected mode applications.
- Extracting ROM constants from the 8087 math coprocessor’s die (righto.com)
Intel introduced the 8087 chip in 1980 to improve floating-point performance on the 8086 and 8088 processors, and it was used with the original IBM PC. Since early microprocessors operated only on integers, arithmetic with floating-point numbers was slow and transcendental operations such as arctangent or logarithms were even worse. Adding the 8087 co-processor chip to a system made floating-point operations up to 100 times faster.
- The stack circuitry of the Intel 8087 floating point chip, reverse-engineered (righto.com)
Early microprocessors were very slow when operating with floating-point numbers. But in 1980, Intel introduced the 8087 floating-point coprocessor, performing floating-point operations up to 100 times faster. This was a huge benefit for IBM PC applications such as AutoCAD, spreadsheets, and flight simulators. The 8087 was so effective that today’s computers still use a floating-point system based on the 8087.
- 8087.martypc.net
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- Intel 8087 (Wikipedia)
The Intel 8087, announced in 1980, was the first floating-point coprocessor for the 8086 line of microprocessors. The purpose of the chip was to speed up floating-point arithmetic operations, such as addition, subtraction, multiplication, division, and square root. It also computes transcendental functions such as exponential, logarithmic or trigonometric calculations. 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.