Windows NT was written to be cross-platform, and it was actually developed on RISC chips -- hence the HAL (Hardware Abstraction Layer). Unlike Linux, it wasn't

Windows NT was written to be cross-platform, and it was actually developed on RISC chips -- hence the HAL (Hardware Abstraction Layer). Unlike Linux, it wasn't written on and for an x86 processor.... At one time, commercial Windows NT PCs were sold with DEC Alpha processors. However, the volume of x86 PC sales drives huge economies of scale that make it hard for other platforms. This actually benefited Linux in particular, but it also encouraged Apple switch from its own hardware to PC-based x86 hardware, which resulted in cheaper Macs. Microsoft has never developed an OS specifically for Intel x86 chips (ie Windows NT and CE: the basis for DOS was bought in) to try to avoid being wholly dependent on Intel. Intel has also supported alternative operating systems to avoid being wholly dependent on Microsoft. But neither is immune from market forces.