Microsoft’s mixed bag of chips
The popular notion that Microsoft only writes for Intel and other x86-compatible processors is, quite simply, wrong.
Microsoft has written two operating systems entirely from scratch that were neither written on nor intended for Intel x86-compatible processors.
Windows NT’s development was started on Intel’s i960 RISC processor and then switched to the MIPS R3000/R4000 after Intel had decided to downplay the i960 and focus on x86 chips instead. NT had a Hardware Abstraction Layer to make it easier to port to different architectures.
The first public release of Windows NT 3.1 in 1993 ran on Intel x86 chips, DEC Alpha and MIPS processors. Windows desktop PCs with DEC Alpha chips went on sale at reasonable prices.
Later, Microsoft added support for IBM’s PowerPC as part of an attempt – along with IBM, Apple and Motorola – to launch a common platform that would run Windows, Mac OS and Unix on the same PC. However, neither IBM nor Apple went through with it.
Windows NT was also ported to run on Intergraph Clipper, Sun Sparc and Intel Itanium chips.
When Microsoft wanted a more lightweight, modular real-time operating system, it started again with a new version called Windows CE.
This was originally released on MIPS and Hitachi SH processors, with version 2 supporting ARM, StrongARM, IBM PowerPC and, finally, Intel x86 chips in 1997.