is disposed on a wall face of a main body of the portable pc 10 for example and is loaded with a pc card 40 conformable with the specifications as made by the personal computer memory association japan electronic industry development association pcmcia jeida the dock i f 34 is a hardware for connecting the portable pc 10 and the docking station 14 in which if the portable pc 10 is set to the docking station an internal bus of the docking station is connected to the dock i f 34 so that various sorts of hardware components connected to the internal bus of the docking station is connected via the dock i f 34 to the pci bus 22 in the case of removing the portable pc 10 from the docking station 14 the eject button 15 provided in the docking station 14 as shown in fig1 may be depressed but a lock mechanism not shown is active at the time of depression so that the portable pc 10 can not be undocked from the docking station 14 and the os 86 performs a preprocessing for removing the portable pc 10 from the docking station 14 and after the end of the preprocessing the.