Information processing system using portable terminal unit and data communication adapter having biased connector

A combination of a portable terminal unit and an optional device, said portable terminal unit being driven by a battery, and equipped with a control circuit, a keyboard, and connectors, to which the optional device for extending a function of the portable terminal unit is connected, the combination comprising:

• a housing of the portable terminal unit, the housing including the control circuit, the keyboard, and the connectors thereupon, said housing including a receiving area for receiving the optional device therein;
• a casing of the optional device, said casing of said optional device comprising
• an opening in said casing;
• an auxiliary connector disposed in said opening, said auxiliary connector for connecting to the portable terminal unit;
• a printed circuit board positioned in the casing, said auxiliary connector being mounted on said printed circuit board;
• a bias means is attached to said printed circuit board, for biasing the printed circuit board from a bottom side thereof toward the opening from a fixed location within the casing;
• and
• a stopper means provided in the opening attached to the casing for retaining and regulating the position of the printed circuit board inside the opening.