[psyc]

Where do you rate the part of the OS that makes 100,000 types, brands, and models of devices all look about the same to our apps? I always saw hardware compatibility and abstraction as the greatest value proposition, not only for the user but for the PC industry as a whole.

[jacquesm]

Hardware abstraction layer. Can be done in userspace, with the exception of a timer. You may need to add some interrupt arbitration logic.