Abstract: A display apparatus of a simple matrix type displays an intermediate tone on a liquid panel by a data thinning-out system. As a modulated alternating inverted signal for determining a polarity of a driving voltage is applied to each pixel of the liquid panel, employed is a signal whose phase is inverted by 180.degree. every tone representing cycle which is a predetermined period of a plurality of frames, and it is structured such that a polarity of the driving voltage to be applied to each pixel is changed according to polarity of the modulated alternating inverted signal. Therefore, a positive polarity portion and a negative polarity portion of an effective voltage to be applied to a pixel in an arbitrary tone representing cycle are completely canceled by a negative polarity portion and a positive polarity portion of the driving voltage to be applied to the pixel in a tone representing cycle adjacent to said arbitrary tone representing cycle respectively.

Abstract: A personal portable computer system includes peripheral devices such as a printer and a CRT which can be driven by a battery power source. The computer system includes a computer body which contains interface units and power supplied to the interface units is controlled. The interface units are used for supplying power to the peripheral devices.

Abstract: An operation halting circuit comprises a circuit for controlling a system which executes a specified operation and a circuit for shutting off every input to the control circuit so as to prevent the supply voltage from being applied to the control circuit when the supply voltage drops below a specified threshold value.