Am5x86

The Am5x86, also known as the Am5x86-P75, is a 486-class microprocessor manufactured by AMD. It was released in October 1995. The Am5x86 was AMD's highest performing x86 processor at the time of its release, and was often considered to be a "drop-in replacement" for older 486 processors, offering significantly improved performance.

The processor featured an internal clock multiplier, allowing it to run at a higher clock speed than its external bus speed. This multiplier was typically set to 2x, meaning a 33 MHz bus speed could result in a 66 MHz processor speed. However, it was often marketed with a "P-rating" system, with the Am5x86-P75 indicating performance roughly equivalent to an Intel Pentium 75 MHz processor. This P-rating was achieved not only through its higher internal clock speed but also through internal architectural improvements over traditional 486 processors, including more advanced branch prediction and a larger cache.

The Am5x86 was manufactured using a 0.35 micrometer process and typically came in a 133-pin PGA (Pin Grid Array) package. It was available in various clock speeds, with 100 MHz and 133 MHz being common, corresponding to 50 MHz and 66 MHz bus speeds respectively. Its ability to significantly boost the performance of existing 486-based systems made it a popular upgrade choice for users who could not afford a full Pentium-based system. It was commonly found in mainstream desktop computers of the mid-1990s.