[citation][nom]spookyman[/nom]No AMD and Intel both share the same x86 development and architecture from working with IBM in the early 80's developing the 286/386 platform for IBM. Or as referred to as the IBM AT.[/citation]
In a word, horsecrap.
Intel was entirely the company developing x86 processors. IBM did insist that Intel have a second source (AMD) before they would commit to using it for the IBM PC.
The PC/AT was NOT a 386. There were three models (officially, although the XT 286 was more of an AT than an XT), the 139, 239, and 339. The first two were 6 MHz with one wait state. Even back then, there were overclockers, although it took a lot more skill than now. People were overclocking the 139s, so IBM put a timing loop in the 239 that prevented running it faster than 6 MHz. They also reduced the size of the motherboard (called Baby AT). The 339 jacked up the clock speed to 8 MHz. There was no 386.
After the PC/AT, IBM introduced the PS/2 line in 1987, with the PS/2 Model 80 as their first 386 machine.