CPSC 120 Lab 5
February 23, 2001

For the fifth lab in the course, you will work on the xTuringMachine Lab, which can be found at


The lab report, which is due at next Friday's lab, consists of Exercises 1, 2, 4, 5, 9 and 11 from that lab. For exercises 1, 2, 4, and 5, you are asked to create Turing Machines to perform certain tasks. For these exercises, you will have to save your work in a file. This is for two reasons. First of all, if you can save your work, you can put it aside for a while and continue working on it later. Second, when I have to grade your work, I will be able to run your machine to make sure that it works. It is very difficult to check a table of rules without being able to run the machine. Unfortunately, the "Save" and "Load" buttons won't work when an applet is run in a Web browser. To solve this problem, you have to run xTuringMachine like a regular program. When you do this, you will be able to save and load files.

To run xTuringMachine for this lab, instead of clicking the "Launch xTuringMachine" button on the Web page for the lab, do the following:

On the Windows desktop, open the My Computer icon, then open the "N" drive (PCCommon), then find and open the folder named "cpsc120". Inside, you will find a program named "RunLabs" (or "RunLabs.bat"). Double-click on this program. A small window will open, listing all the standard labs for The Most Complex Machine. In this window, click on the button named "xTuringMachine Lab".

Note that you can run the programs for any of the labs in the same way, as long as you are on a Windows computer on the HWS network.

In this version of the xTuringMachine applet, you will be able to load and save files. For example, you could save your Turing machines on your "M" drive. For exercises 1, 2, 4, and 5, I would like you to save your machines in a place where I can get at them for grading. You can put them in your account on math.hws.edu. To do this, you need to access this account under Windows. Fortunately, this is easy. You can mount your math account as a Windows drive, just like your "M" drive is mounted:

To mount your math.hws.edu account on your Windows desktop: Right-click the "My Computer" icon, and select "Map Network Drive" from the pop-up menu. A small dialog box will open. In the box labeled "Path", enter \\math\username where username is your user name. (The "Drive" can be anything you like. Check the box labeled "Reconnect at Logon" if you want your math account to be automatically added to your Windows desktop every time you log on.) When you hit "OK", your math account will be added to "My Computer" and a window will open showing your files on math.hws.edu.

Now, when you save a file in xTuringMachine, you can save it in your math.hws.edu account. I have access to the files that you put there, and I will look at and run your machines when I grade the lab.

On your written lab report, for exercises 1, 2, 4, and 5, tell me whose account I should look in to find the Turing Machine files and what the names of the files are. In addition to the machine for each of these exercises, you should write a short description of the process that your machine uses to perform its task You might get partial credit for your write-up even if you don't have a working machine. Exercises 9 and 11 are essay questions that you should answer in writing in your lab report.