IBM 80486 66MHz
IBM's version of the DX2/66 was actually made by Cyrix. On the bottom on the CPU a Cyrix logo can be found.
While AMD used Intels 386 architecture to build their 486, Cyrix used reverse engineering to develop it. The early Cyrix 486 chips are somewhat slower compared to Intel or AMD's 486 chips but sold for less money as well. IBM also made their own CPU's based upon the Intel 386SX architecture and sold it as 486DLC. Those CPU's are enhanced 386 CPU's with more cache and things like that.

