The hardware How well documented are the parts? base machine open docs actually working CPU 100% 100% Chipset 95% 95% boot process 95% 95% clocks 100% 100% serial 100% 100% peripherals drive controller 90% 98% ethernet 95% 99% display 60% 100% basics, problems for X 802.11 wireless 15% 95% other devices hit and miss (percentage of "what people have", not "types of devices")