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CPU Dos and Don'ts: How to Reduce Problems To minimize problems encountered while running CPU Simulation Software: DO:
Why you should you avoid moving or renaming files and folders:
Troubleshooting
Several possibilities exist:
The simulators frequently crash. How can I prevent that? CPU Simulation Software draw heavily upon a computer's graphic resources and consume much of the memory devoted to graphics. Simulators draw on the graphic resources most heavily when they load setup files. The computer does not "forget" that a simulator was opened until you quit Internet Explorer. If you open four or five simulators in a row and each simulator loads a setup, the computer must allocate graphics resources all five simulators. That can easily overload the computer's graphics resources and cause Internet Explorer to crash. Your computer might even freeze. If this happens, you need to force-quit Internet Explorer. On a PC, type ALT-CNTRL-DELETE (strike all three keys at once). On a Macintosh, type APPLE-OPTION-ESC (strike all three keys at once). If you need to reboot the computer, on a PC type ALT-CNTRL-DELETE twice rapidly. On a Macintosh, type APPLE-CONTROL-START (that is, the button you normally use to start the computer). You can reduce this problem by simply quitting Internet Explorer after you have opened three or four simulators in a row. Before you open another simulator, quit Internet Explorer by closing all Explorer windows (PCs) or typing APPLE-Q (Macs). See the list of Dos and Don'ts above. Note: Like many programs, the CPU simulators do crash for other reasons. If the crashes become frequent and don't appear to be caused by memory or graphics resources problems, consult the on-line FAQ at the web site for the CPU Project, or report the problems to The Learning Team.
The simulators run slowly, take a long time to open, or the computer runs out of memory trying to open a simulator. How can I improve the simulator performance? PCs: Virtual Memory is turned on by default. If you have trouble running the simulators, you may have virtual memory turned off, or your hard drive may be almost full. To check the virtual memory, right-click on My Computer and choose Properties. In the Properties window, click on the Performance tab. Click on the Virtual Memory button at the bottom of the Performance tab. If Virtual Memory is off, turn it on! If the computer is managing your virtual memory, check to see which disk the computer is using. Look in the first grayed window under Let me specify my own virtual memory settings. By default, the computer uses C drive. Since you probably use C drive heavily, C drive may be almost full. If C drive has less than 100 MB available for Virtual Memory (or even if available memory is close to 100 MB), click on the "Let me..." button and change the drive to one that has more available memory. Another option is to create more room on your hard drive. Click OK and restart your computer. Hopefully, your simulators will run somewhat faster. If you still have problems, check your computer's system and software against the System Requirements.
Macintoshes: Turn on Virtual Memory and allocate 96 MB to it. To do this, click on the Apple icon in the upper left corner of the computer screen. On the menu that opens (the Apple menu), move the cursor down to Control Panels. A Control Panels submenu will open up. Select the Memory control panel. In the Memory control panel, you will see a panel for Virtual Memory. Click the On button. In the field below the word "Available built-in memory," move the counter up to 96 MB or 30 MB less than the "Available on disk" memory (30 MB less so you have some room left on your hard drive), whichever is lower. You can have more hard drive memory dedicated to Virtual Memory, but 96 MB should be sufficient for most purposes. Once you have set the Virtual Memory, restart your computer. If you still have trouble with speed, check your Java security settings (see the answer to the last question above).
I used Save HTML to save a setup. I open the setup file but the simulator does not load. Why didn't it work? You probably did not save the file with the extension .htm or save it in the same folder as the original simulator. Read about Save HTML here, or consult the Save HTML Help page. Also, you need to open the file that ends in .htm, not the file that ends with the compound suffix .htm.setup0 (which is also created by Save HTML). The latter file contains the actual set-up data. The web page (i.e., the file that ends in .htm) loads this data after it loads the simulator.
I was working in a simulator. I clicked on the Back button to return to the index. But the simulator just reloaded. Why can't I return to the index? You probably had this problem with the Current Electricity or Force & Motion simulator. To return to the index:
Clicking on the Back button once takes you to the Force & Motion or Current Electricity Index. However, the code for the index is written so that, if the index has only one link, Internet Explorer immediately jumps to that link. To stop on the Force & Motion or Current Electricity Index, you need to add a simulator set-up to the index. See the description of the Save HTML button for brief instructions on how to do this.
How can I get the simulators to load more quickly on my Macintosh? Your Java programs may be taking a while to load because Internet Explorer is performing security checks on the Java code (e.g., checking the code for viruses). Although this is technically a good security precaution and makes sense with regard to Java applets you encounter on the World Wide Web, this level of security is redundant for Java applets stored on your own computer that you use repeatedly. For that reason, you might try reducing the security precautions so that the CPU simulators load more swiftly. For security reasons, we suggest that you use every simulator at least once before taking the steps below. Start Internet Explorer. In the Internet Explorer window, click on the Preferences button. If the toolbar is not showing, open the Edit menu and select Preferences.
Click OK. Then quit Internet Explorer. Warning: This "fix" is partial at best. The CPU Simulation Software generally load more quickly on PCs than they do on Macintoshes, provided the PCs and Macintoshes are otherwise equal (processing speed, RAM, etc.).
The simulators used to work. Now they don't. Why? What can I do about it? You may have gotten a new operating system or made some other changes to your computer. If so, try updating Internet Explorer and/or the Java virtual machine. PCs: Update Internet Explorer at http://www.microsoft.com/windows/ie/. Update the Microsoft Java Virtual Machine at http://www.microsoft.com/java/. Macintoshes: Update Internet Explorer at http://www.microsoft.com/mac/ie/default.asp. Update Macintosh Run-time for Java at http://www.apple.com/java/. If updating the software does not work, consult the CPU Simulators FAQ.
On-line Help and Contact Information For additional help, consult the home page of the Constructing Physics Understanding Project, http://cpuproject.sdsu.edu/cpu/. In particular, consult the CPU Simulators FAQ. In addition, you can consult The Learning Team®. Go to their home page, http://www.learningteam.org, or call The Learning Team at (914) 273-2226.
Checking/Setting Classpaths Manually Only set classpaths yourself if absolutely necessary. The Installers set classpaths automatically. You can follow the steps below to simply check the classpaths (except those where you change them, of course). PCs: From the Start menu, select Run. In the Run field, type "regedit.exe". Before making any changes to the Registry Editor, open the Registry menu and select Export Registry File. In the Export window, save the registry as regeditOLD.reg on your desktop. Export Range should be All. This step is simply INSURANCE. If something goes wrong below, you can always reinstall your old Registry by double-clicking on regeditOLD.reg. On the left, open HKEY_LOCAL_MACHINE. Then open SOFTWARE. Under SOFTWARE, open Microsoft. Under Microsoft, select (click once on) Java VM. On the right, you'll find (under Name) an item called Classpath. Double-click on this item. In the window, add the locations of cpu.jar and soundlab.jar. Separate entries with semi-colons. For example: Remove any old references to cpu.jar or soundlab.jar. Click OK. Then close the Registry Editor. Macintoshes: Start Internet Explorer. Click on the Preferences button. Within the Preferences window, click the arrow by Web Browser (left window) and choose Java from the items beneath the Web Browser heading. In the window Class Paths on the right, click Add. Find and select the file cpu.jar in the folder containing CPU software. Repeat for soundlab.jar. Click OK and quit Internet Explorer.
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