After reading about Fn-C found these functions:-
Fn-B my most usfull one.
Fn-2 — enter BIOS setup (during boot)
Fn-B — toggles whether a sleeping OQO will wake when its screen is slid open
Fn-J — toggles freefall detection (no sound = enabled, click = disabled)
Fn-K — toggles audible key clicks
Fn-M — flips screen 180 degrees (does not flip tablet)
Fn-N — toggles direction of scroll wheel
Fn-V — toggles verbose click sounds (clicks are heard when disabling functions, even if key clicks are off)
Fn-Z — toggles TrackStik click-to-select
New function added in BIOS update (version 1.01.44):
Fn-C — enables “gravity mouse”. Causes the mouse to drift in whatever direction you tilt the OQO. Each time you press Fn-C the sensitivity is increased. There are 6 sensitivity settings — hitting Fn-C the 7th time turns it off. It is also turned off when the OQO is rebooted.