Portable apparatus having a flat panel type display unit

A portable computer has a keyboard and a display unit mounted to a base unit. The base unit is equipped with a battery for generating a reference voltage. The display unit has a plasma display and a housing for containing the plasma display. This housing is rotated to an open position for permitting visual confirmation of plasma display at the time of display of an image. In the housing of the display unit is retained a voltage converter for converting the reference voltage of the battery into a drive voltage for driving the plasma display. The voltage converter, which self-generates heat during its converting operation, is arranged on the right or left sides of the plasma display rotated to the open position or above the plasma display.