If you wanted to do only one task and do it the same way every time, you would do better with a customchip design -- what the engineers call an application specific integrated circuit.
That chip, along with the custom charging circuitry developed by OLPC and Marvell means that the tablet can be charged by a hand crank at a 10:1 ratio (10 minutes of usage time for every minute spent cranking), or by the optional four watt solar panel cover at a 2:1 ratio on sunny days.