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Wikipedia / Am486

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 40MHz 486 at or below Intel's price for a 33MHz 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 66MHz 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 8KiB Write-Back L1-Cache, later versions even got an upgrade to 16KiB Write-Back L1-Cache.

The 133MHz 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

Model

FSB

Clock speed

VCore

L1-Cache

Introduced

Am486 DX-25

25MHz

5 V

8 KiB WT

Am486 DX-33

33MHz

Am486 DX-40

40MHz

Apr 1993

Am486 SX-33

33MHz

Am486 SX-40

40MHz

Am486 DE2-66

33MHz

66MHz

3.3 V

1996(?)

Am486 DX2-50

25MHz

50MHz

5 V

Apr 1993

Am486 DX2-66

33MHz

66MHz

5/3.3 V

Sep 1994

Am486 DX2-80

40MHz

80MHz

Sep 1994

Am486 SX2-50

25MHz

50MHz

5 V

Am486 SX2-66

33MHz

66MHz

Apr 1994

Am486 DX4-75

25MHz

75MHz

3.3 V

Am486 DX4-90

30MHz

90MHz

3.3 V

Am486 DX4-100

33MHz

100MHz

3.3 V

1995

Am486 DX4-120

40MHz

120MHz

3.3 V

Enhanced Am486 DX2-66

33MHz

66MHz

3.3/3.45 V

8/16 KiB WB

Enhanced Am486 DX2-80

40MHz

80MHz

8 KiB WB

Enhanced Am486 DX4-75

25MHz

75MHz

Enhanced Am486 DX4-100

33MHz

100MHz

8/16 KiB WB

Enhanced Am486 DX4-120

40MHz

120MHz

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

References