I've been searching internet, using all manner of phrases to find a circuit diagram for what should be a pretty simple project. What I'm hoping to build is a KVM (Keyboard / Video / Mouse) switch circuit for my computer. A single keyboard, monitor, and mouse plug into the circuit, and the circuit is connected to the corresponding ports of two separate computer towers. Normally computer #1 sends/recieves the input/output to the peripherals. Flip a single switch, and the inputs/outputs are directed to computer #2. In essence, a multiple-pole, double-throw switch. I have asked around, and been told that multiplexing ICs are the key. I have several DM74ALS157 ICs on hand, and have attempted to build a simple circuit toggling between two LEDs using the attached diagram, but I've been unable to get a reaction out of it. My electronics knowledge is sporadic; I can follow along in some technical discussions, and while I might not always understand how something works, I have no trouble following diagrams.