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RapidCAD
RapidCAD is a specially packaged Intel 486DX and a dummy floating point unit (FPU) designed as pin-compatible replacements for an Intel 80386 processor and 80387 FPU. Because the i486DX has a working on-chip FPU, a dummy FPU package is supplied to go in the Intel 387 FPU socket. The dummy FPU is used to provide the FERR signal, necessary for compatibility purposes. Despite being able to execute instructions in the same number of cycles as an i486DX, integer performance on RapidCAD suffers due to the absence of level 1 cache and the bottleneck of the 386 bus. RapidCAD offers minimal improvement in integer performance over a 386DX (typically 10%, at most 35%), but provides substantial improvement in floating point operations (up to 80% faster) for which it was marketed. Floating point performance is mostly improved by moving the FPU onto the CPU core. File:KL intel RapidCAD1.jpg, Intel RapidCAD-1 File:KL intel RapidCAD2.jpg, Intel RapidCAD-2 Technical specifications Intel RapidC ...
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Intel 80386
The Intel 386, originally released as 80386 and later renamed i386, is a 32-bit microprocessor introduced in 1985. The first versions had 275,000 transistorsmit.edu—The Future of FPGAs
(Cornell) October 11, 2012
and were the CPU of many s and high-end s of the time. As the original implementation of the

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Intel 486
The Intel 486, officially named i486 and also known as 80486, is a microprocessor. It is a higher-performance follow-up to the Intel 386. The i486 was introduced in 1989. It represents the fourth generation of binary compatible CPUs following the 8086 of 1978, the Intel 80286 of 1982, and 1985's i386. It was the first tightly- pipelined x86 design as well as the first x86 chip to include more than one million transistors. It offered a large on-chip cache and an integrated floating-point unit. A typical 50 MHz i486 executes around 40 million instructions per second (MIPS), reaching 50 MIPS peak performance. It is approximately twice as fast as the i386 or i286 per clock cycle. The i486's improved performance is thanks to its five-stage pipeline with all stages bound to a single cycle. The enhanced FPU unit on the chip was significantly faster than the i387 FPU per cycle. The intel 80387 FPU ("i387") was a separate, optional math coprocessor that was installed in a ...
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Intel 80486 OverDrive
Intel's i486 OverDrive processors are a category of various Intel 80486s that were produced with the designated purpose of being used to upgrade personal computers. The OverDrives typically possessed qualities different from 'standard' i486s with the same speed steppings. Those included built-in voltage regulators, different pin-outs, write-back cache instead of write-through cache, built-in heatsinks, and fanless operation — features that made them more able to work where an ordinary edition of a particular model would not. Each 486 Overdrive typically came in two versions, ODP and ODPR variants. The ODPR chips had 168 pins and functioned as complete swap-out replacements for existing chips, whereas the ODP chips had an extra 169th pin, and were used for inserting into a special 'Overdrive' (Socket 1) socket on some 486 boards, which would disable the existing CPU without needing to remove it (in case that the existing CPU is surface-mounted). ODP chips will not work in ...
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Pentium OverDrive
The Pentium OverDrive was a microprocessor marketing brand name used by Intel, to cover a variety of consumer upgrade products sold in the mid-1990s. It was originally released for 486 motherboards, and later some Pentium sockets. Intel dropped the brand, as it failed to appeal to corporate buyers, and discouraged new system sales. 486 sockets The Pentium OverDrive is a heavily modified, 3.3 volt Pentium P54 core manufactured on 0.6 micrometer technology. It is fitted with a 486-compatible bus unit (though with an increased pin-count), an integrated heatsink and fan, and 32 kB of level 1 cache, double the 16 kB offered on regular P54C chips. As the data bus was effectively reduced to 32-bit width, per-clock performance was much lower than that of a 'regular' Pentium, though still substantially faster compared to a similarly clocked 486 owing to the Pentium's architectural improvements, such as the much improved FPU. It was also equipped with an integrated 3.3 volt power regula ...
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Floating Point Unit
Floating may refer to: * a type of dental work performed on horse teeth * use of an isolation tank * the guitar-playing technique where chords are sustained rather than scratched * ''Floating'' (play), by Hugh Hughes * Floating (psychological phenomenon), slipping into altered states * Floating exchange rate, a market-valued currency * Floating voltage, and floating ground, a voltage or ground in an electric circuit that is not connected to the Earth or another reference voltage * Floating point, a representation in computing of rational numbers most commonly associated with the IEEE 754 standard * ''Floating'' (film), a 1997 American drama film Albums and songs * ''Floating'' (Eloy album) (1974) * ''Floating'' (Ketil Bjørnstad album) (2005) * ''Floating'' (EP), a 1991 EP by Bill Callahan * "Floating" (The Moody Blues song) (1969) * "Floating" (Megan Rochell song) (2006) * "Floating" (Jape song) (2004) * "Floating", a song by Jolin Tsai from the 2000 album '' Don't Stop' ...
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Intel 80387
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 (''Numeric Processor eXtension''). 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 ma ...
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Intel 387
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 (''Numeric Processor eXtension''). 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 ma ...
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