In order to overcome the relatively short battery life and the relatively long delay between the activation and the actual functioning of a typical mobile computing system, the mobile computing system is provided with a personal computer (PC) architecture system and a personal digital assistant (PDA) architecture system, and a common display and shared peripherals. Interfacing to the systems is a super input output or embedded controller (SIO/EC) that acts as a slave device to whatever system has control of computing system. The SIO/EC controls a quick switch which blocks or allows communication along communication busses connecting the systems to the SIO/EC. A user can selectively change, by way of a user interface to the SIO/EC, to whatever system that is desired by the user.