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The Am486 is a 80486-class family of computer
Computer

A computer is a machine that manipulates Data according to a list of Code .The first devices that resemble modern computers date to the mid-20th century , although the computer concept and various machines similar to computers existed earlier....
 processors
Central processing unit

A central processing unit is an electronic circuit that can execute computer programs. This broad definition can easily be applied to many early computers that existed long before the term "CPU" ever came into widespread usage....
 that was produced by AMD in the 1990s. Intel beat AMD to market by nearly four years, but AMD priced its 40 MHz 486 at or below Intel's price for a 33 MHz chip, offering about 20% better performance for the same price. Early AMD 486 chips were drop-in replacements for their Intel counterparts, but later AMD clock-doubled 486s ran at 3.3 volts instead of Intel's 5 volts, which limited their suitability as upgrade chips until third-party voltage adapters appeared on the market.

While competing 486 chips, such as those from Cyrix
Cyrix

Cyrix was a Central processing unit manufacturer that began in 1988 in Richardson, Texas as a specialist supplier of high-performance math coprocessors for Intel 80286 and Intel 80386 systems....
, benchmarked lower than the equivalent Intel chip, AMD's 486 matched Intel's performance on a clock-for-clock basis.

While the Am386
Am386

The Am386 central processing unit was released by AMD in 1991. A IBM PC compatible of the Intel 80386 design, it sold millions of units and positioned AMD as a legitimate competitor to Intel Corporation, rather than just a second source for x86 CPUs ....
 was primarily used by small computer manufacturers, the Am486DX, DX2, and SX2 chips gained acceptance among larger computer manufacturers, especially Acer
Acer (company)

Acer Incorporated is a Taiwanese multinational electronics manufacturer. It owns the largest franchised computer retail chain in Taipei, Taiwan....
 and Compaq
Compaq

Compaq Computer Corporation was an United States personal computer company founded in 1982, and is now a brand name of Hewlett-Packard Company....
, in the 1994 time frame.

AMD's higher clocked 486 chips provided superior performance to many of the early Pentium
Pentium

Introduced on March 22, 1993, the original Pentium was the first superscalar x86 architecture microprocessor. Its fifth-generation x86 microarchitecture was a direct extension of the 80486 architecture with dual integer pipeline s, a faster FPU unit, wider data bus, and features for further reduced address calculation latency....
 chips, especially the 60 and 66 MHz launch products.






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The Am486 is a 80486-class family of computer
Computer

A computer is a machine that manipulates Data according to a list of Code .The first devices that resemble modern computers date to the mid-20th century , although the computer concept and various machines similar to computers existed earlier....
 processors
Central processing unit

A central processing unit is an electronic circuit that can execute computer programs. This broad definition can easily be applied to many early computers that existed long before the term "CPU" ever came into widespread usage....
 that was produced by AMD in the 1990s. Intel beat AMD to market by nearly four years, but AMD priced its 40 MHz 486 at or below Intel's price for a 33 MHz chip, offering about 20% better performance for the same price. Early AMD 486 chips were drop-in replacements for their Intel counterparts, but later AMD clock-doubled 486s ran at 3.3 volts instead of Intel's 5 volts, which limited their suitability as upgrade chips until third-party voltage adapters appeared on the market.

While competing 486 chips, such as those from Cyrix
Cyrix

Cyrix was a Central processing unit manufacturer that began in 1988 in Richardson, Texas as a specialist supplier of high-performance math coprocessors for Intel 80286 and Intel 80386 systems....
, benchmarked lower than the equivalent Intel chip, AMD's 486 matched Intel's performance on a clock-for-clock basis.

While the Am386
Am386

The Am386 central processing unit was released by AMD in 1991. A IBM PC compatible of the Intel 80386 design, it sold millions of units and positioned AMD as a legitimate competitor to Intel Corporation, rather than just a second source for x86 CPUs ....
 was primarily used by small computer manufacturers, the Am486DX, DX2, and SX2 chips gained acceptance among larger computer manufacturers, especially Acer
Acer (company)

Acer Incorporated is a Taiwanese multinational electronics manufacturer. It owns the largest franchised computer retail chain in Taipei, Taiwan....
 and Compaq
Compaq

Compaq Computer Corporation was an United States personal computer company founded in 1982, and is now a brand name of Hewlett-Packard Company....
, in the 1994 time frame.

AMD's higher clocked 486 chips provided superior performance to many of the early Pentium
Pentium

Introduced on March 22, 1993, the original Pentium was the first superscalar x86 architecture microprocessor. Its fifth-generation x86 microarchitecture was a direct extension of the 80486 architecture with dual integer pipeline s, a faster FPU unit, wider data bus, and features for further reduced address calculation latency....
 chips, especially the 60 and 66 MHz launch products. While equivalent Intel 80486DX4
Intel 80486DX4

The Intel IntelDX4 is a clock-tripled 80486 microprocessor with 16kb L1 cache. Intel named it deceptively during litigation with AMD over trademarks....
 chips were priced high and required a minor socket modification, AMD priced low. Intel's DX4 chips initially had twice the cache of the AMD chips, giving them a slight performance edge, but AMD's DX4-100 usually cost less than Intel's DX2-66.

The enhanced Am486 series supported new features like extended power-saving modes and Write-Back L1-Cache, later versions even got an upgrade to 16 KiB Write-Back L1-Cache.

The 133 MHz AMD Am5x86 was a higher clocked enhanced Am486.

Am486 models

Model Clock speed
Clock rate

The clock rate is the fundamental rate in cycles per second for the frequency of the clock in any synchronous circuit. For example, a crystal oscillator frequency reference typically is synonymous with a fixed sinusoidal waveform, a clock rate is that frequency reference translated by electronic circuitry into a corresponding square wav...
 		 VCore L1-Cache Introduced
Am486 DX-25 25 MHz 5 V 8 KiB WT
Am486 DX-33 33 MHz 5 V 8 WT
Am486 DX-40 40 MHz 5 V 8 WT April 1993
Am486 SX-33 33 MHz 5 V 8 WT
Am486 SX-40 40 MHz 5 V 8 WT
Am486 DE2-66 66 MHz 3 V 8 WT 1996(?)
Am486 DX2-50 50 MHz 5 V 8 WT April 1993
Am486 DX2-66 66 MHz 5/3.3 V 8 WT
Am486 DX2-80 80 MHz 5/3.3 V 8 WT
Am486 SX2-50 50 MHz 5 V 8 WT
Am486 SX2-66 66 MHz 5 V 8 WT 1994
Am486 DX4-75 75 MHz 3.3 V 8 WT
Am486 DX4-100 100 MHz 3.3 V 8 WT 1995
Am486 DX4-120 120 MHz 3.3 V 8 WT
Enhanced Am486 DX2-66 66 MHz 3.3/3.45 V 8/16 WB
Enhanced Am486 DX2-80 80 MHz 3.3/3.45 V 8 WB
Enhanced Am486 DX4-75 75 MHz 3.3/3.45 V 8 WB
Enhanced Am486 DX4-100 100 MHz 3.3/3.45 V 8/16 WB
Enhanced Am486 DX4-120 120 MHz 3.3/3.45 V 8/16 WB


WT = Write-Through cache strategy, WB = Write-Back cache strategy

External links

  • AMD Am486 processor images and descriptions