The last processor designed by Intel that AMD produced was the AM486 (80486), and it was released in 1994. Due to ongoing legal disputes between Intel and AMD, some versions of the AM486 use Intel microcode whereas others use microcode developed in-house by AMD. AMD followed a similar strategy with its AM486 as it did with the AM386, by pushing clock speed considerably higher than Intel. Although Intel's fastest 80486 processors were capped at 100 MHz, AMD went as high as 120 MHz on the AM486.
Not long after, in 1995, AMD also released its AMD 5x86. This processor used the same architecture as the AM486 and 80486, but it pushed the clock speed even higher. Retail models ran at 133 MHz, and OEMs had access to an even faster 150 MHz version.
Other notable changes in this line of processors was the addition of L1 cache, which helped to increase performance compared to the older 80386/AM386 CPUs. It also moved the FPU into the same package as the CPU, which also significantly improved performance. Prior to this, all FPUs were sold as separate hardware units and connected to the CPU through the motherboard.
Following the release of Intel's first Pentium processor around the same time also lead AMD and other competing CPU designers to introduce the PR or "Pentium Rating" system. This gave companies a simple way to advertise their products against each other and against Intel's Pentium. An example of this is the AMD 5x86 PR 75, which was advertised as having equivalent performance to a 75 MHz Pentium CPU.
AM486 And AMD 5x86
|Code Name|| N/A || X5 |
|Date|| 1993 || 1995 |
| Architecture || 32-bit || 32-bit |
|Data Bus|| 32-bit || 32-bit |
|Address Bus|| 32-bit || 32-bit |
|Maximum Memory Support|| 4 GB|| 4 GB|
| L1 Cache|| 8 - 16 KB || 16 KB |
| L2 Cache||None||None|
|Clock Speed|| 16 - 120 MHz || 133 -150 MHz |
| FSB || 16 - 50 MHz || 33 - 50 MHz |
| FPU || Integrated || Integrated |
| SIMD ||None|| None |
|Fab||800 - 1000 nm || 350 nm |
|Transistor Count|| 1,185,000 || N/A |
|Power Consumption|| N/A || N/A |
|Voltage|| 5 V - 3.3 V || 3.45 V |
|Die Area||67 - 81 mm² ||N/A|
|Socket|| 168 pins || 168 pins |