From Wikipedia the free encyclopedia

AMD Am486DX 40 MHz
AMD Am486DX2 66MHz
AMD Am5x86-P75
AMD Am486 DX2-66 die shot
AMD Enhanced Am486 DX4-120 die shot
AMD Élan SC450 in Nokia 9000 Communicator

The Am486 is a 80486-class family of computer processors 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, benchmarked lower than the equivalent Intel chip, AMD's 486 matched Intel's performance on a clock-for-clock basis.

While the Am386 was primarily used by small computer manufacturers, the Am486DX, DX2, and SX2 chips gained acceptance among larger computer manufacturers, especially Acer and Compaq, in the 1994 time frame.

AMD's higher clocked 486 chips provided superior integer performance to many of the early Pentium chips, especially the 60 and 66 MHz launch products. While equivalent Intel 80486DX4 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 an 8 KiB 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.

One derivative of the Am486 family is the core used in the AMD Élan SC4xx family of microcontrollers marketed by AMD.



Am486 models

Am486DE2-66 with power management for embedded systems.
Model FSB Clock speed VCore L1-Cache Introduced
Am486 DX-25 25 MHz 5 V 8 KiB WT
Am486 DX-33 33 MHz
Am486 DX-40 40 MHz Apr 1993
Am486 SX-33 33 MHz
Am486 SX-40 40 MHz
Am486 DE2-66 33 MHz 66 MHz 3.3 V 1996(?)
Am486 DX2-50 25 MHz 50 MHz 5 V Apr 1993
Am486 DX2-66 33 MHz 66 MHz 5/3.3 V Sep 1994[1]
Am486 DX2-80 40 MHz 80 MHz Sep 1994[1]
Am486 SX2-50 25 MHz 50 MHz 5 V
Am486 SX2-66 33 MHz 66 MHz Apr 1994[1]
Am486 DX4-75 25 MHz 75 MHz 3.3 V
Am486 DX4-90 30 MHz 90 MHz 3,3 V
Am486 DX4-100 33 MHz 100 MHz 3.3 V 1995
Am486 DX4-120 40 MHz 120 MHz 3.3 V
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 8 KiB WB
Enhanced Am486 DX4-75 25 MHz 75 MHz
Enhanced Am486 DX4-100 33 MHz 100 MHz 8/16 KiB WB
Enhanced Am486 DX4-120 40 MHz 120 MHz

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


  1. ^ a b c "Am486/5x86". CPU MUSEUM. Retrieved 2017-07-19.