DirectionsThis logic simulation applet allows you to place circuit elements in the drawing area, move them around using drag and drop, connect them, and then simulate the resulting circuit's behavior. On the right side of the screen is a series of buttons which perform functions to help you build your circuit. At the bottom of the screen is a table which allows you to enter values for the inputs to your circuit so you can run a simulation with different test cases.The remainder of the screen consists of the drawing area. You may place objects anywhere on the drawing area and then move them around as you wish. To select an object, click on it or inside of it. It will become red to indicate that it is selected. You may then move it or perform an operation on it by clicking one of the buttons to the left. You can select multiple objects by holding down Shift or Control as you click. It is recommended that you do not select more than 2 objects at a time for performing operations, as the behavior of the applet has not yet been expanded to handle that situation. Button DescriptionsAdd The Add button allows you to add the circuit element currently selected in the drop-down list to the left of the add button. After you click Add, the selected element will be created wherever you click in the drawing area. Typically you would add some inputs, some logic gates, and one or more outputs, then connect them using the other buttons described below.Delete The Delete button deletes the selected gate, as well as any wires attached to its inputs or to its outputs. Connect The Connect button creates a wire between two gates. The simulator assumes that logic will flow from left to right, so the output of the left-most gate will be connected to the input of the right-most gate. If a gate as multiple inputs/outputs, you will be asked which port you wish to use for the new connection. Ports are numbered from top to bottom starting at one. Thus a two-input nand gate would have two ports, the top port being port one and the bottom port being port two. Disconnect Disconnects the two selected gates. When this button is pressed, as search is performed for a common wire between two gates. When that wire is found it is deleted. If there is more than one wire between two gates, only the first wire will be deleted. Wired OR Makes a gate behave as if a fabrication error caused a wired OR at its inputs. If the resulting output signal differs from the error-free signal, the color of the output signal will be either blue or magenta instead of black or red. Wired AND Makes a gate behave as if a fabrication error caused a wired AND at its inputs. If the resulting output signal differs from the error-free signal, the color of the output signal will be either blue or magenta instead of black or red. Simulate Takes the input values specified in the input table, applies them to the inputs of the circuit, and simulates the new output of the circuit. Wire ColorsWires that are low are black.Wires that are high are red. Wires that are high because of an error are magenta. Wires that are low because of an error are blue. |