 Welcome to Demultiplexers. In this video, you'll learn how Demultiplexers transmit data and data select lines determine the specific output through which data is passed, which will prepare you for a short three-question quiz at the end of this video. A Demultiplexer is a digital switching device that has one input and several outputs. The function of a Demultiplexer is to transmit data, which enters its input line, and maps the input to one of its output lines. Data select lines determine the specific output through which data is passed. The signals that are present on the data select line determine which of the output pins the input signal is mapped to. Here a Demultiplexer that maps a single input signal to one of eight outputs. In order to specify which of the eight outputs to map the input signal to, three data select lines are necessary. The truth table in this figure shows all possible combinations of the data select lines A, B, and C. The values of the data select lines represent numbers in binary. The combinations of A, B, and C present a range of numbers from zero, zero, zero, which represents the number zero, to one, one, one, which represents the number seven. When the data select lines have the values zero, zero, zero, the input signal becomes mapped to output zero. This is continued for each possible combination of the data select lines, including the final possible combination in the truth table, one, one, one, which causes the input signal to map to output seven. In addition to the input data line and the data select lines, there is another input called the strobe or enable line. The purpose of this input is to allow the demultiplexer to function normally or be disabled by not allowing data from the input to be passed to any of the outputs. The enable line in this diagram is an active low input. If a logic zero is applied to the enable line, the demultiplexer will function properly. Based on the logic state that's applied to the enable line, observe how the signal applied to the data select line causes data to be passed to the corresponding output from the data input line. Notice when the enable input receives a low logic signal, then the demultiplexer operates normally. However, if a logic one is applied to the enable line, then the demultiplexer becomes disabled and data from the input will not be passed to any of the output lines. When the enable input is set to a logic high, regardless of what's going on with other inputs, it'll be ignored because the whole system is disabled. The number of data select lines in a demultiplexer determines the number of outputs the demultiplexer has. As each of the data select lines has two possible values, zero or one, the total number of outputs is two raised to the power of the number of data select lines. For example, if a demultiplexer has two data select lines, then it will have four outputs. Three data select lines will result in eight outputs. Four results in sixteen outputs, and so on and so on. Notice how with every additional data select line, the number of outputs doubles. With two data select lines, there are four outputs. Three data select lines has eight outputs, and four data select lines has sixteen outputs. Now that you're familiar with how the demultiplexer functions, choose the letter of the correct answer that completes these statements. You can pause the video if you'd like more time to think about your answers. The correct answer is one input, A, to be passed to one of several outputs, D. The correct answer for question two is true. And finally, the correct answer for question three is D, five. This completes the demultiplexers. Thanks for watching. If this video was helpful, please give us a thumbs up.