 Seven-segment displays are found in many common household appliances. For example, a microwave oven displays the time when not in use. A typical display has four seven-segment light emitting diodes, or LEDs. The microwave is programmed to operate by pressing the various buttons to display cooking settings, such as the length of time food is to be cooked. When the timer expires, the display will flash on and off at the same time and alarm sounds to let you know the food is done. A microcontroller inside the microwave push button panel monitors what buttons are pushed and updates the display. The microcontroller also monitors sensors inside the microwave to turn the electronic components on and off and to display the oven status. Each of the four single seven-segment displays is composed of LEDs that can be selectively activated to display digits from one to nine. Let's look at a single seven-segment LED display. Each of the segments, A through G, contains a separate LED which can be controlled individually. Each of the input pins connects to a specific LED segment. By inputting an eight-digit binary number to the corresponding pins of the seven-segment digital display, a particular number can be formed by activation of specific LEDs. For example, to display a zero, a binary string input of ones at pins A through F and a zero at G will activate all the segments but segment G. To display a five, all but pins B and E would need an input of one. Seven is formed when pins A, B, and C get an input of one while the other pins receive zeros. A nine can be generated by inputting ones to all but the E pin and so on for the remaining numbers. Thus, the LEDs of a microwave can be precisely controlled to display numbers that report its operational status.