Click here to download and then run the Window's Logisim application. You can learn about Logisim beyond the scope of this lab from the Logism website.

Begin by creating a very simple circuit just to get the feel for placing gates and wires.

1. Start by clicking the "And Gate" button. This will cause the shadow of an And Gate to follow your cursor around. Click once within the main schematic window to place an And Gate.

2. Click the "Input Pin" button. Now place two Input Pins somewhere to the left of your And Gate.

3. Click the "Output Pin" button. Then place an Output Pin somewhere to the right of your And Gate. Your schematic should look something like this at this point:

4. Click the "Add Wires" button. Click and drag to connect the dots at the right side of the Input Pins to the left side of the And Gate. This will take several steps, as you can only draw vertical and horizontal wires. Just draw a wire horizontally, release the mouse button, then click and drag down starting from the end of the wire to continue vertically. You can attach to the And Gate anywhere on the left side.

Repeat the same procedure to connect the right side of the And Gate to the Output Pin. After completing these steps your schematic should look roughly like this:

5. Finally, click the "Change Values" button and try clicking on the Input Pins in your schematic. Observe what happens. Does this match with what you think an And Gate should do?

Much like C and MIPS programs can contain sub-procedures, a schematic can contain subcircuits. In this part of the lab we will create several subcircuits to demonstrate their use.

1. Create a new schematic (File->New) for your work.

2. Create a new subcircuit (Project->Add Circuit ). You will be prompted for a name for the subcircuit; call it NAND.

3. In the new schematic window that you see create a simple NAND circuit with 2 Input Pins on the left side and an Output Pin on the right side.

4. Go back to your "main" schematic by double-clicking "main" in the circuit selector at the left of the screen. Your original (blank) schematic will now be displayed, but your NAND gate has been stored.

5. Now, single click the word "NAND" in the list. This will tell Logisim that you wish to add your "NAND" circuit into your "main" circuit.

6. Try placing your NAND gate into the "main" schematic. If you did it correctly, you should see a gate with 2 inputs on the left and one output on the right. Try hooking up Input Pins and Output Pins to these and test if it works as you expect.

7. Repeat these steps to create several more subcircuits. In addition to NAND, create the following: NOR, XOR, 2 to 1 MUX, and 4 to 1 MUX. Do not use any built in gates from Logisim other than AND, OR, and NOT. However, once you've built a subcircuit, you may use it to build others.

Hint: Look at the lecture slides for a refresher on how to build these. You may want to consider using some of your custom subcircuits when designing the others.