AMD Am486DX 40 MHz
AMD Am486DX2 66MHz
AMD Am5x86-P75
AMD Am486 DX2-66 die shot
AMD Enhanced Am486 DX4-120 die shot

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 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.

Features

Am486 models

Am486SX2-66.
Am486DE2-66 with power management for embedded systems.
ModelFSBClock speedVCoreL1-CacheIntroduced
Am486 DX-2525 MHz5 V8 KiB WT
Am486 DX-3333 MHz
Am486 DX-4040 MHzApr 1993
Am486 SX-3333 MHz
Am486 SX-4040 MHz
Am486 DE2-6633 MHz66 MHz3.3 V1996(?)
Am486 DX2-5025 MHz50 MHz5 VApr 1993
Am486 DX2-6633 MHz66 MHz5/3.3 VSep 1994[1]
Am486 DX2-8040 MHz80 MHzSep 1994[1]
Am486 SX2-5025 MHz50 MHz5 V
Am486 SX2-6633 MHz66 MHzApr 1994[1]
Am486 DX4-7525 MHz75 MHz3.3 V
Am486 DX4-90 30 MHz 90 MHz 3,3 V
Am486 DX4-10033 MHz100 MHz3.3 V1995
Am486 DX4-12040 MHz120 MHz3.3 V
Enhanced Am486 DX2-6633 MHz66 MHz3.3/3.45 V8/16 KiB WB
Enhanced Am486 DX2-8040 MHz80 MHz8 KiB WB
Enhanced Am486 DX4-7525 MHz75 MHz
Enhanced Am486 DX4-10033 MHz100 MHz8/16 KiB WB
Enhanced Am486 DX4-12040 MHz120 MHz

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

References

  1. 1 2 3 "Am486/5x86". CPU MUSEUM. Retrieved 2017-07-19.
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