Cyrix Cx486

It primarily competed with the Intel 486 with which it was software compatible, would operate in the same motherboards provided proper support by the BIOS was available and generally showed comparable performance.

The processor did, however, sport a 2KB Write-back cache and a special "Write-Burst" signal which offered a slight performance boost in certain applications provided the motherboard was capable of utilizing the feature.

[4] Users could upgrade the processor to 486DX specifications through use of an accessory, the Cyrix Cx487S which was an x87 Floating Point Unit coprocessor which fit between the CPU and the socket on the motherboard.

Codenamed M6, the Cyrix Cx486DX is essentially the same as the Cx486S except it featured an internal Floating Point Unit and quadruple the amount of cache memory.

Despite the faster clock speeds, the 50 MHz version of this processor was less popular than the other models Cyrix had produced.

[6] This is reflected by Intel and AMD processors operating at 50 MHz where their sales show a similar trait of being less popular.

Users could potentially negate this by increasing latency for the memory, cache and bus but this would also cause performance to drop.

Introduced in September 1995, it was otherwise not vastly different to the older designs and proved to be competitive both performance-wise and price-wise against offerings from AMD and Intel though it was later to market than its competitors.

A Cyrix-designed SGS-Thomson processor. SGS sold Cyrix processors under their own label as per their contract.
A Cyrix Cx486S processor. Compatible with the Intel 486SX.
The Cyrix Cx487S FPU coprocessor, installed between CPU and motherboard socket.
Die shot of Cx486S-33.
Die shot of Cx486DX-40.
Cyrix Cx486DX2 rated for 66MHz operation.
Die shot of Cx486DX2-V66.
Die shot of Texas Instruments TI486DX2-G66.