Cyrix Cx486
The Cx486 CPU family from Cyrix is an in-house development that is compatible with the i486 CPUs.
history
Since Cyrix did not have a patent exchange agreement with Intel, the function of the 80486 CPUs was copied. The result was a family of microprocessors that worked in the same socket and with the same software as their Intel counterparts, but had a different internal structure and some of the functions included expanded (or even fewer).
With the Cx486 CPUs, Cyrix succeeded in entering the x86 business. As a fabless company, Cyrix needed production partners - in this case IBM , SGS-Thomson and Texas Instruments - who could sell these CPUs under their own names as part of the agreement. A CPU was launched under four different names.
In addition to the "pure" 80486-compatible CPUs, Cx486 CPUs were also developed that were suitable for 80386 mainboards and their sockets. These CPUs were ideal upgrade CPUs for corresponding mainboards.
Naming
The naming was largely based on Intel's naming for the i486 CPUs:
- DX: models with math coprocessor (equivalent to Intel i486DX )
- DX2: Like DX, but with internal clock doubling (corresponds to Intel i486DX2 )
- DX4: Like DX, but with internal clock tripling (corresponds to Intel DX4 )
- S: models without math coprocessor (equivalent to Intel i486SX )
There are also the following models:
- DLC: Models for 80386 socket without math coprocessor
- DRx²: Like DLC, but with internal clock doubling
- DRu²: PGA package, internal clock doubling
- SLC: Like DLC, but with a QFP package instead of the more popular PGA package
- SRx²: Like SLC, but with internal clock doubling
Models
See also
- Am486 family
- i486 family
- UMC Green CPU