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Encyclopedia > Intel 80486
486
Central processing unit

The exposed die of an Intel 80486DX2 microprocessor.
Produced: From 1989 to 2007
Common Manufacturers:
CPU Speeds: 16 MHz to 133 MHz
FSB Speeds: 16 MHz to 50 MHz
Process:
(MOSFET channel length)
0.8 µm
Instruction Set: x86 (i386)
Sockets:

The Intel486[1] brand refers to Intel's family of i486 (incl. i487) CPUs - the second generation of 32-bit x86 microprocessors, and the first truly pipelined x86 design. Their predecessor was the Intel386, the very first 32-bit x86 processor. The first line of 486 processors was introduced in 1989 containing 1.2 million transistors (800 nanometer technology). The i486 was so named without the usual 80-prefix, because of a court ruling that prohibited trademarking numbers (like 80486). Intel dropped number-based naming altogether with the successor to the i486 – the Pentium processor. Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ... Image File history File links Download high resolution version (1341x1002, 803 KB) Summary Macro shot of an Intel 80486DX2 die in its packaging. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... Advanced Micro Devices, Inc. ... Texas Instruments (NYSE: TXN), better known in the electronics industry (and popularly) as TI, is an American company based in Dallas, Texas, USA, renowned for developing and commercializing semiconductor and computer technology. ... Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ... A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... In computers, the front side bus (FSB) or system bus is the physical bi-directional data bus that carries all electronic signal information between the central processing unit (CPU) and the northbridge. ... A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... The metal-oxide-semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is by far the most common field-effect transistor in both digital and analog circuits. ... It has been suggested that some sections of this article be split into a new article entitled instruction set architecture. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... The Intel 80386 is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 1994 and later. ... Socket 1 was the second of a series of standard sockets created by Intel into which various x86 microprocessors were plugged. ... Socket 2 was one of the series of standard sockets into which various x86 microprocessors were plugged. ... Intels Socket 3 was a type of CPU socket into which various x86 microprocessors were inserted. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation in Macleans College is often known as Ash Lim. ... 32-bit is a term applied to processors, and computer architectures which manipulate the address and data in 32-bit chunks. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ... The Intel386[1] is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 2007. ... The 800 nanometer (800 nm or 0. ... This article does not cite any references or sources. ...

Contents

Improvements

From a software point of view, the instruction set of the i486 CPUs is very similar to its predecessor, the Intel386, with the addition of only a few extra instructions, such as CMPXCHG which executes the Compare-and-swap atomic operation and the XADD which executes the Fetch-and-add atomic operation. Though many atomic instructions have existed since the 8086/8088 because of the nature of the x86 instruction set (the most common were the XCHG instruction, which have many purposes, such as executing the Test-and-set atomic operation, and the ADD instruction which could be used to execute the Fetch-and-add atomic operation, except it could not return the original value, and the 80386 added many more (such as the BTS and BTC instructions, which can be used to execute the Test-and-set operation against individual bits), they did not correspond to the atomic instructions implemented in many other processors, particularly RISC processors, which made it harder to port applications from these processors, and sometimes they were simply not adequate. It has been suggested that some sections of this article be split into a new article entitled instruction set architecture. ... CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation in Macleans College is often known as Ash Lim. ... The Intel386[1] is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 2007. ... In computer science, the compare-and-swap CPU instruction is a special instruction that atomically compares the contents of a memory location to a given value and, if they are the same, modifies the contents of that memory location to a given new value. ... In computer science, the fetch-and-add CPU instruction is a special instruction that atomically tests and modifies the contents of a memory location. ... The 8086 is a 16-bit microprocessor chip designed by Intel in 1978, which gave rise to the x86 architecture. ... The Intel 8088 is an Intel microprocessor based on the 8086, with 16-bit registers and an 8-bit external data bus. ... In computer science, the test-and-set instruction is an instruction used to atomically write to a memory location. ... In computer science, the fetch-and-add CPU instruction is a special instruction that atomically tests and modifies the contents of a memory location. ... In computer science, the test-and-set instruction is an instruction used to atomically write to a memory location. ...


From a hardware point of view, however, the architecture of the i486 is a vast improvement. It has an on-chip unified instruction and data cache, an optional on-chip floating-point unit (FPU) (original and DX models), and an enhanced bus interface unit. In addition, under optimal conditions, the processor core can sustain an execution rate of one instruction per clock cycle. These improvements yield a rough doubling in performance over an Intel386 at the same clock rate. A 386 (or 286) chip therefore has to reach 50 MHz to be comparable with low end parts in the 486 series. Diagram of a CPU memory cache A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. ... A floating point unit (FPU) is a part of a CPU specially designed to carry out operations on floating point numbers. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers and typically is controlled by device driver software. ... It has been suggested that this article or section be merged into Clock signal. ... The Intel386[1] is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 2007. ... AMD 80286 at 12 MHz. ...

The 486DX2 architecture.
The 486DX2 architecture.

Image File history File links Download high resolution version (1409x994, 70 KB) The i486DX2 architecture. ... Image File history File links Download high resolution version (1409x994, 70 KB) The i486DX2 architecture. ...

Differences between the 386 and 486

  • Data/Instruction Cache — An 8192-byte SRAM built into the processor core, designed to store the most commonly used instructions. The 386 supported an off-chip cache, but this was much slower.
  • Pipelining — This allows the processor to handle a Locate-Fetch-Execute each clock cycle. The pipeline is offset meaning the execute step required information from the previous two clock cycles. A locate would feed the next fetch, the fetch would feed the next execute. The 386 needs to do each step separately.
  • Improvements to MMU performance
  • Integrated FPU — (DX models only) Added accelerated high end math functions.

The 486 has a 32-bit data bus and a 32-bit address bus. This requires either four matched 30-pin SIMMs or one 72-pin SIMM. A 32-bit address bus means that 4 GiB of memory can be directly addressed. Look up cache in Wiktionary, the free dictionary. ... SRAM can stand for: Squash Racquets Association of Maharashtra An official body of squash game in Maharashtra, India System Replacement and Modernization Short-Range Attack Missile Static Random Access Memory Shadow Random Access Memory Sideways Random Access Memory Service régional dadmission du Montréal métropolitain SRAM (bicycles... MMU is the initialism (acronym) for: Manchester Metropolitan University Manned Maneuvering Unit, in astronautics Memory management unit, in computer architecture Mono Methyl Urea, in chemistry Multimedia University, a private university in Malaysia Myanmar Maritime University, a school of science and engineering under the Ministry of Transport of Myanmar Government. ... A floating point unit (FPU) is a part of a computer system specially designed to carry out operations on floating point numbers. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers. ... An address bus is (part of) a computer bus, used by CPUs or DMA-capable units for communicating the physical addresses of computer memory elements/locations that the requesting unit wants to access (read/write). ... 30- (top) and 72-pin (bottom) SIMMs. ... The term gib may refer to: a castrated male cat or ferret an abbreviation for gibibyte (GiB) or gibibit (Gib) an abbreviation for Gibraltar an abbreviation for Gib Board, itself an abbreviation of Gibraltar Board, all Winston Wallboards[1] tradenames for drywall (plasterboard). ...


The Intel project manager for the 80486 was Pat Gelsinger. Pat Gelsinger was the first Chief Technology Officer of Intel Corporation. ...


In May 2006 Intel announced that production of the 80486 would cease at the end of September 2007. [1] Although the chip had long been obsolete for personal computer applications, Intel had continued production for use in embedded systems. What is an Embedded System? Electronic devices that incorporate a computer(usually a microprocessor) within their implementation. ...


Models

An Intel i486DX-33 microprocessor
An Intel i486DX-33 microprocessor

There are several suffixes and variants including: Image File history File linksMetadata Download high resolution version (980x1004, 670 KB)Intel_80486DX-33 This picture is taken by Weihao. ... Image File history File linksMetadata Download high resolution version (980x1004, 670 KB)Intel_80486DX-33 This picture is taken by Weihao. ...

  • i486 — The original chip (without any clock doubling).
  • i486SX — an i486DX with the FPU part disabled or missing. Early variants were parts with disabled (defective) FPUs, later versions has the FPU removed from the die to reduce area and hence cost.
  • i486DX — newer versions of the original i486.
  • i486DX2 — the internal processor clock runs at twice the clock rate of the external bus clock.
  • i486SX2 — i486DX2 with the FPU disabled.
  • i486SL — i486DX with power conservation circuitry. Mainly for use in portable computers.
  • i486SL-NM — i486DX with power conservation circuitry; SL enhanced suffix, denotes a i486 with special power conservation circuitry similar to that in the i486SL processors.
  • i487 — i486DX with a slightly different pinout sold as FPU to i486SX systems; it was widely documented that i487 when installed completely disables the existing i486SX on mother board.
  • i486 OverDrive — i486SX, i486SX2, i486DX2 or i486DX4. Marked as upgrade processors, some models had different pinouts or voltage handling abilities from 'standard' chips of the same speed stepping.
  • i486DX4 — designed to run at triple clock rate (not quadruple as often believed; the DX3, which was meant to run at 2.5x the clock speed, was never released).

Internal clock rates included 16, 20, 25, 33, 40, 50, 66, 75 and 100 MHz. The 486DX2 66 MHz was the most widespread high-end 486 chip, while more powerful iterations such as the OverDrive and DX4 were less used in favour of the succeeding Pentium. The only 486 that ran a 50 MHz bus, the i486DX 50 MHz chip, had compatibility problems with boards and components because of this high bus speed requirement. 486DX 50 MHz was a rather unpopular chip and was quickly replaced by the clock-doubled i486DX2 chips which ran the bus at half of the CPU clock speed. The Intel 80486SX is an Intel 486DX microprocessor with its floating-point unit (FPU) disconnected. ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ... An Intel i486DX2-66 Microprocessor, top view ... and bottom view with gold plated pins. ... It has been suggested that this article or section be merged into Clock signal. ... The Intel 80486SL is the power-saving variant of the Intel 80486DX microprocessor. ... The Intel 80487, or 487 (i487), was the floating-point arithmetic coprocessor for the Intel 486SX chips. ... Sony Playstation motherboard A motherboard, also known as main board, logic board or system board, is the central or primary circuit board making up a complex electronic system, such as a computer. ... Intel 80486 OverDrive processors were a category of various Intel 80486s that were produced with the designated purpose of being used to upgrade personal computers. ... The Intel DX4 is a clock-tripled 80486 microprocessor chip. ... This article does not cite any references or sources. ... An Intel i486DX2-66 Microprocessor, top view ... and bottom view with gold plated pins. ...


Competitive alternatives

486 processor by UMC
486 processor by UMC

486 compatible processors have been produced by other companies such as IBM, Texas Instruments, AMD, Cyrix, UMC, and Chips and Technologies. Some are near duplicates in terms of specifications and performance, some are not. The 486 was, however, covered by many of Intel's 386 patents as well as some of its own. Intel and IBM have broad cross-licenses of these patents, and AMD was granted rights to the relevant patents in the 1995 settlement of a lawsuit between the companies.[2] Image File history File links Metadata No higher resolution available. ... Image File history File links Metadata No higher resolution available. ... International Business Machines Corporation (IBM, or colloquially, Big Blue) (NYSE: IBM) (incorporated June 15, 1911, in operation since 1888) is headquartered in Armonk, New York, USA. The company manufactures and sells computer hardware, software, and services. ... Texas Instruments (NYSE: TXN), better known in the electronics industry (and popularly) as TI, is an American company based in Dallas, Texas, USA, renowned for developing and commercializing semiconductor and computer technology. ... Advanced Micro Devices, Inc. ... Cyrix corporate logo Cyrix was a CPU manufacturer that began in 1988 as a specialist supplier of high-performance math co-processors for 286 and 386 systems. ... UMC (United Microelectronics Corporation) was founded in 1980, as Taiwans first Semiconductor company. ... Chips and Technologies was the first fabless semiconductor company, a model developed by its founder Gordon Campbell. ...


Platform

With regards to the 486 system platform, early 486 machines were equipped with only 16-bit and 8-bit ISA slots. Later motherboards combined ISA with the high-speed VESA Local Bus (VLB), primarily for video cards and hard drive controllers. Prior to this some motherboards came equipped with 32 bit versions of the ISA standard called: EISA. These were supplanted with VLB and later PCI. The final 486 boards came equipped with PCI and ISA, and sometimes VLB as well (though in this configuration VLB suffered performance-wise). Bus speed was determined by multipliers for ISA, but PCI and VLB bus clocks were often equal to the clock of the 486 bus (some boards had multipliers for these as well). Image File history File links Size of this preview: 421 × 600 pixelsFull resolution (563 × 802 pixel, file size: 620 KB, MIME type: image/png) This image is of a magazine cover, and the copyright for it is most likely owned by either the publisher of the magazine or the individual... In computer science, 16-bit is an adjective used to describe integers that are at most two bytes wide, or to describe CPU architectures based on registers, address buses, or data buses of that size. ... 8-bit refers to the number of bits used in the data bus of a computer. ... This article does not cite any references or sources. ... A motherboard is the central or primary circuit board making up a complex electronic system, such as a modern computer. ... This article or section does not cite any references or sources. ... This article does not cite any references or sources. ... 64-bit PCI expansion slots inside a Power Macintosh G4 The Peripheral Component Interconnect, or PCI Standard (in practice almost always shortened to PCI), specifies a computer bus for attaching peripheral devices to a computer motherboard. ...


One of the earliest complete systems to use the 80486 chip was the Apricot VX FT, produced by United Kingdom hardware manufacturer Apricot Computers. Even overseas in the United States it drew attention as "The World's First 486" in a popular September 1989 issue of Byte magazine (shown right). Apricot Computers, a British manufacturer of business-orientated personal computers, was the new name for Applied Computer Techniques (ACT) in 1985. ... December 1975 issue of Byte (Vol 1. ...


Later 486 boards also supported Plug-And-Play, the Microsoft technology that began as a part of Windows 95 designed to make component installation easier for consumers. Plug and Play is a term used in the computer field to describe a computers ability to have new devices, normally peripherals, added to it without having to restart the computer. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ... Windows 95 is a consumer-oriented graphical user interface-based operating system. ...


References

  1. ^ Microprocessor Hall of Fame. Intel. Retrieved on 2007-08-11.

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 223rd day of the year (224th in leap years) in the Gregorian calendar. ...

See also

This generational and chronological list of Intel microprocessors attempts to present all of Intels processors from the pioneering 4-bit 4004 (1971) to the present high-end offerings, the 64-bit Itanium 2 (2002) and Intel Core 2 and Xeon 5100 and 7100 series processors (2006). ... The Motorola 68040 is a microprocessor from Motorola. ... Motorola Inc. ...

Notes

This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL. This article does not cite any references or sources. ... Bold text // “GFDL” redirects here. ...


External links

  • http://users.erols.com/chare/486.htm
  • Intel 80486 images and descriptions at cpu-collection.de
  • CPU-INFO: 80486, indepth processor history

  Results from FactBites:
 
INTEL 80486 (500 words)
The Intel 80486 (i486, 486) is a range of Intel CISC microprocessors which is part of the Intel x86 family of processors.
Intel 80486SX - a 486DX with its FPU disabled.
Intel 80486 OverDrive - 486SX, 486SX2, 486DX2 or 486DX4.
Intel 80486 - Wikipedia, the free encyclopedia (972 words)
The Intel i486 (also called 486 or 80486) is a range of 32-bit scalar Intel CISC microprocessors which is part of the Intel x86 family of processors.
Intel 80486 OverDrive - i486SX, i486SX2, i486DX2 or i486DX4.
Intel and IBM have broad cross-licenses of these patents, and AMD was granted rights to the relevant patents in the 1995 settlement of a lawsuit between the companies.
  More results at FactBites »

 
 

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