An earlier 486-compatible CPU chip from AMD introduced in 1993. Two years later, AMD came out with the Am5x86, which was a higher-speed 486-compatible chip used in new PCs and sold as an upgrade to 486 systems. The Am5x86 had a built-in "clock quadrupling" feature, which let it run at 133 MHz and match a 75 MHz Pentium in performance. The Am5x86 was also overclocked up to 160 MHz and beyond by many enthusiasts. See
AMD.