The First ARM-Based Windows RT Devices Arrive

Windows RT devices reached consumers in late 2012, including Microsoft’s Surface RT. They ran on ARM processors rather than the x86 CPUs that had defined Windows PCs for decades.

Windows RT looked like Windows 8 and included a desktop version of Office, but users could not install ordinary x86 desktop programs. Store applications compiled for the Windows Runtime could support both architectures, but the existing Windows software library did not magically become portable.

The distinction was difficult to communicate. Two devices could look almost identical while supporting very different software. Technically, Windows RT demonstrated that Microsoft could bring much of Windows to ARM; commercially, it showed how strongly the value of Windows depended on backward compatibility.