Abstract: A data processor composed of: a main body including a CPU, a keyboard provided at the top of the main body, a pair of sliding rails provided at both sides of the keyboard, a pair of sliders each for sliding on one of the sliding rails, a lid pivotably connected to the sliders and a display panel attached on one face of the lid. When the data processor is not used, the sliders are moved to the rear end, and the lid is tilted down, whereby the keyboard is covered by the lid. When the keyboard is used, the lid is raised up with the sliders at the rear end. After the keyboard operation is finished, the sliders are (and the lid is) moved to the front end. When the lid is tilted down with the sliders at the front end, the data processor becomes compact and the display panel can be seen from the outside. Since the keyboard is covered by the lid, the keys are secured from mistouches, and the operator can see the display without bending low.

Abstract: A thermal printer/plotter provided with a thermal printhead having a plurality of aligned thermal resistive elements divided into several groups for sequential driving of one group after another and simultaneous energization of the selected ones of the thermal resistive elements in each one of the groups; a DC power source having a current capacity smaller than the amount of current required for simultaneous energization of all the thermal resistive elements included in each one of the groups; a capacitor of a larger current capacity connected in parallel with the thermal resistive elements so as to discharge a sufficient amount of current to be added to the amount of current supplied by the DC power source if the latter amount is not sufficient; and control means for determining the period of time for the capacitor having been discharged to be charged again to a predetermined level in accordance with the number of the thermal resistive elements that have been energized in each one of the groups, and effectin