The Am486 is a 80486-class family of computer

Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

 processors

Central processing unit

The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...

 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.

While competing 486 chips, such as those from Cyrix

Cyrix

Cyrix Corporation was a microprocessor developer that was founded in 1988 in Richardson, Texas as a specialist supplier of high-performance math coprocessors for 286 and 386 microprocessors. The company was founded by former Texas Instruments staff members and had a long but troubled relationship...

, 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 CPU was a 100%-compatible clone of the Intel 80386 design released by AMD in 1991. It sold millions of units, positioning AMD as a legitimate competitor to Intel, rather than being merely 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 multinational information technology and electronics corporation headquartered in Xizhi, New Taipei City, Taiwan. Acer's products include desktop and laptop PCs, tablet computers, servers, storage devices, displays, smartphones and peripherals...

 and Compaq

Compaq

Compaq Computer Corporation is a personal computer company founded in 1982. Once the largest supplier of personal computing systems in the world, Compaq existed as an independent corporation until 2002, when it was acquired for US$25 billion by Hewlett-Packard....

, in the 1994 time frame.

AMD's higher clocked 486 chips provided superior performance to many of the early Pentium chips, especially the 60 and 66 MHz launch products. While equivalent Intel 80486DX4

Intel 80486DX4

The IntelDX4 is a clock-tripled i486 microprocessor with 16 kB L1 cache. Intel named it DX4 as a consequence of 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 a 8 KiB

Kibibyte

The kibibyte is a multiple of the unit byte for quantities of digital information. The binary prefix kibi means 1024; therefore, 1 kibibyte is . The unit symbol for the kibibyte is KiB. The unit was established by the International Electrotechnical Commission in 1999 and has been accepted for use...

 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	FSB	Clock speed Clock rate The clock rate typically refers to the frequency that a CPU is running at.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 wave...	VCore CPU core voltage The CPU core voltage is the power supply voltage supplied to the CPU , GPU, or other device containing a processing core...	L1-Cache	Introduced
Am486 DX-25	25 MHz	25 MHz	5 V	8 KiB Kibibyte The kibibyte is a multiple of the unit byte for quantities of digital information. The binary prefix kibi means 1024; therefore, 1 kibibyte is . The unit symbol for the kibibyte is KiB. The unit was established by the International Electrotechnical Commission in 1999 and has been accepted for use...  WT
Am486 DX-33	33 MHz	33 MHz	5 V	8 KiB WT
Am486 DX-40	40 MHz	40 MHz	5 V	8 KiB WT	April 1993
Am486 SX-33	33 MHz	33 MHz	5 V	8 KiB WT
Am486 SX-40	40 MHz	40 MHz	5 V	8 KiB WT
Am486 DE2-66	33 MHz	66 MHz	3 V	8 KiB WT	1996(?)
Am486 DX2-50	25 MHz	50 MHz	5 V	8 KiB WT	April 1993
Am486 DX2-66	33 MHz	66 MHz	5/3.3 V	8 KiB WT
Am486 DX2-80	40 MHz	80 MHz	5/3.3 V	8 KiB WT
Am486 SX2-50	25 MHz	50 MHz	5 V	8 KiB WT
Am486 SX2-66	33 MHz	66 MHz	5 V	8 KiB WT	1994
Am486 DX4-75	25 MHz	75 MHz	3.3 V	8 KiB WT
Am486 DX4-100	33 MHz	100 MHz	3.3 V	8 KiB WT	1995
Am486 DX4-120	40 MHz	120 MHz	3.3 V	8 KiB WT
Enhanced Am486 DX2-66	33 MHz	66 MHz	3.3/3.45 V	8/16 KiB WB
Enhanced Am486 DX2-80	40 MHz	80 MHz	3.3/3.45 V	8 KiB WB
Enhanced Am486 DX4-75	25 MHz	75 MHz	3.3/3.45 V	8 KiB WB
Enhanced Am486 DX4-100	33 MHz	100 MHz	3.3/3.45 V	8/16 KiB WB
Enhanced Am486 DX4-120	40 MHz	120 MHz	3.3/3.45 V	8/16 KiB WB

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

External links

• AMD: Enhanced Am486 Microprocessors
• AMD: 30 Years of Pursuing the Leader. Part 2
• cpu-collection.de AMD Am486 processor images and descriptions