I recently found on a website a PDA (Google Android 7 Touch Screen WiFi Tablet PC Netbook PDA Notebook Computer UMPC MID 128MB RAM 2GB HD Silver L7002G03 [L7002G03]- $100.31: TinyDeal, Mobile Phone, MP4/MP3, PC/Game Gadgets, Watch), which is said to be compatible with the Google Android operating system. But its RAM is just 128MB. I want to know how much of an RAM would be occupied by the OS. Besides, what can PDA can do when the Android system is working?