Abstract: A digital-to-analog conversion method includes outputting one priority bit of a digital signal to a digital output port to produce a respective output signal. An output time for the output signal is obtained by multiplying a unit of time by a weight of coding representing the significance of the bit, to define a period of time of maintaining the signal level at the output port before shifting to a next bit, and repeating the aforesaid steps for the successive bits. The output signal produced can be used to directly drive a power switching means for linear control of a power element, or integrated and filtered to provide a level analog output.

Abstract: An interactive instant response broadcast board comprises a microcomputer and a plurality of display broadcast boards and a plurality of detecting elements arranged thereon that detect the movement of objects detected in front of the broadcast boards, and transmits information to the microcomputer. A host server transmits and receives information to and from broadcast boards and extracts the information read from the microcomputer and detected by the detecting elements, and downloads the image messages and programs to at least one broadcast board for displaying. The broadcast board may be used in public place without being connected to a network.