We’ve already discussed the software distribution changes that are going in to the ARM versions of Windows 8; this post will focus on hardware. Windows 8 on ARM (WOA hereafter) has been built in close cooperation with Texas Instruments, Qualcomm, and Nvidia.
The omission of Samsung is a bit surprising given the latter’s Exynos product line, strong tablet lineup, and the fact that Samsung built the Windows 8 x86 tablets Microsoft gave away at Build last fall. It’s not clear at this point if Samsung’s plans for Windows 8 revolve primarily around x86 products, or if the company decided to sit out on becoming a developer partner.
One of the most significant challenges Microsoft had to overcome was the degree of variation that can occur between ARM developers. In the PC world, the battle over interface standards has been over for decades — but there was once a reason why users’ referred to the PCI card installation process as “plug and pray.” In WOA, the ACPI firmware has been extended to address and understand how SoC devices are configured in order to ensure it can enumerate them properly. The Windows HAL (Hardware Abstraction Layer) that handles things like interrupts and DMA in conventional PCs has also been modified and extended to support current and future SoCs.