As we mentioned in the Read Me file, “How Computers Work” requires 2 MB of free RAM to operate. (Note: Don’t set the application size to a lower number—out of memory errors will result.) With 4 MB, you’re going to be close to exhausting RAM while running “How Computers Work” under System 7. For best performance, free up as much RAM as possible by following the steps below.
First, a quick list of things to change when you need more RAM (and who doesn’t?), in order of most likely to succeed:
• add a fleet of SIMMS
• Quit any open applications
• remove any nonessential system extensions
• lower the Memory Control Panel disk cache setting (called RAM cache in System 6.0x)
• turn on Virtual Memory (System 7 only—read on for description of icky side effects)
• restart the Mac
Check the Memory setting (Control Panel) to make sure your Mac isn’t using up RAM with a high Cache Size setting. Set it as low as it will go (probably 32K). In the screen shot below, the user is adjusting the Cache Size downward.
Pruning System Extensions
System extensions, also known as INITs or CDEVs, are bits of code that run during your machine’s startup. Often, they are represented by icons that appear momentarily on the bottom of the screen as they load. There are four places the Mac system software checks to find them: (1) in the Extension folder, (2) the Control Panels folder, (3) loose inside the System folder and (4) in the Startup Items folder.
How much RAM do your extensions use? To find the elusive answer, restart your machine and check the “About This Macintosh” information (Apple Menu). If “Largest Unused Block” shows that you have at least 2000K available, there may be no need for changes.
If the number is lower than 2000K, check to see if any applications are active, as in the example above. If so, quit out of them and re-check available memory. If the number is still lower than 2000K, restart your Mac again, this time holding down the shift key until you see the “extensions off” message displayed. This will prevent all System extensions from loading. Again check the “About This Macintosh” information. Subtracting the new “Largest Unused Block” number from the previous will quickly tell you how much RAM your System extensions are using. If your Mac featured a pretty healthy extension load, you will notice a correspondingly healthy gain in the “Largest Unused Block” number.
Next, temporarily disable non-essential extensions by removing them to a designated folder tucked elsewhere on your hard drive. If you have a software extension manager, use it to “turn off” unnecessary extensions during startup. If you don’t, here is a way to accomplish the same thing:
You can see that our Mac user in this example has created four folders, one for each corresponding extension holding area in the system folder, and is now removing one non-essential item to a holding folder. This beats trying to remember where you had things stored before the shakeup.
Note that you will want to leave in many standard Apple extensions (such as Monitors, Memory, Sound, LaserWriter), in addition to QuickTime 1.5 and your CD-ROM driver software.
Once non-essential extensions are relocated, restart your Mac. If available RAM is significantly better than 2000K, you can add the removed extensions—one at a time—back into their original homes. You have to do it one at a time, restarting after each addition, in order to see which extensions are taking up all the room.
If the new number is still less than 2000K, you may need to remove screen fonts and/or sounds from your System file. Do this by opening the System file itself (in the System folder) and moving nonessential sounds and fonts to a holding folder located elsewhere. Note: leave Chicago, Geneva and Monaco and at least one sound in your System file.
System 6.0x: Since these use far less RAM than System 7, 4 MB operation isn’t that tricky. Exceptions will be in cases where many screen fonts have been installed into the System file or where a large number of extensions have been placed into the System folder. To remove fonts out of the System file, use the Font DA Mover and create another suitcase to hold them—they can be easily reinstalled at any time. To remove non-essential INITs and CDEVs, just drag them out of the System folder and into a temporary holding folder. Make sure you don’t remove QuickTime 1.5 or your CD-ROM driver. Note: If you are using Multifinder, try switching to Finder (Option menu: Set Startup)— this may get you all the RAM you need. Also check the RAM cache setting in the Control Panel (General) to make sure it is either very low or (better) turned off.
Miscellaneous Problems & Messages
Problem: You can’t hear audio while "How Computers Work” is playing.
Solution: “How Computers Work” does not produce sound out of the CD player. All sound comes out of the Mac internal speaker or external audio jack. First, check to make sure you haven’t inadvertently hit the “S,” “F12,” or Keypad “/,” any of which will toggle audio on and off. Next, check the Sound Control Panel. Open it and turn the volume up to 6 or higher. Check to see if any sound is coming from the Mac.
If you still hear nothing, check to make sure you don’t have anything plugged into the audio jack on the rear panel of the Macintosh. (If something is plugged in, try turning up the volume on the attached device.) If the audio jack is open and you still hear nothing when you submit the above test, restart your Mac and try again.
Problem: While audio is playing, you hear clicks, dropouts or other glitches.
Solution: Check the Memory Control Panel and verify that Virtual Memory is turned off. If you are using File Sharing, try turning it off as well. (Although having File Sharing turned on shouldn’t in itself be a problem, you will have difficulties when other users try to access your system.) Also check to make sure that QuickTime version 1.5—not an older version—is installed in your System folder.
If none of these morsels prove helpful, then take a look at your CD-ROM drive unit. “How Computers Work” is designed to work with an Apple CD SC drive. If your drive is slower than this model, it may not be fast enough to play glitch-free audio. Some models that may have problems include:
NEC CDR-36 and CDR-72
EMAC Metro CD
Chinon CDA-431
Pioneer/Relax DRM-600
(Note that this list may reflect out-of-date information, and as such is intended only as a guideline—not an authoritative reference.)
Problem: Soon after launching the program, you notice that a blank white box appears.
Solution: You are using an old version of QuickTime. Update to QuickTime version 1.5 (provided in the Support folder on the "How Computers Work” CD-ROM) and move the other one very far away.
Problem: The whole program seems excessively slow—even slower than a CD-ROM should be.
Solution: Remember that the access time for a CD-ROM is much, much slower than that of a hard disk, and this will translate into slower responses from your computer. You can improve this by moving the application itself, e.g., “How Computers Work,” onto the root (first) level of your hard disk. This is also true for the sample applications.
There may, however, be other factors affecting the speed of your computer. If your internal (startup) drive is more than about 80% full, or if it sees frequent use, it may be fragmented. Use an optimizing utility to check it. Second, there are certain utilities—usually optimizing and diagnostic programs—that run in the background while allowing you to do other work. You should these off while “How Computers Work” is running, since they interfere with CPU speed. Finally, if you have a large enough amount of RAM, you can improve speed if you set the application size of “How Computers Work” to 2500K or higher.
Problem: When played on a hi-fi audio system or headphones, the audio sounds scratchy.
Solution: The “How Computers Work” audio should sound fine on the Macintosh speaker, for which it was designed. If you use a hi-fi system or headphones, however, you may hear some hiss or scratchiness. This is normal and results from aliasing problems with the 8-bit audio samples. The noise can be reduced by applying a low-pass audio filter or turning down the treble on the tone controls.
Problem: After playing movies for several minutes at a stretch, audio seems to get out of synch with video.
Probable Cause: There is an anomaly in Apple’s system software that causes this to happen. This may be particularly noticeable on an LC running under 6.07. To eliminate the problem, click on the movie. A controller bar will appear. Click twice on the controller’s pause/play button to pause and play the movie and it will be in synch this time.
Problem: CD player works fine sometimes, doesn’t at other times. Occasionally you may even have trouble starting your Macintosh.
Solution: Make sure your SCSI chain (which consists of your CD-ROM and any other drive to your Mac) is properly terminated, i.e., the last device is terminated and each device has a distinct ID number. Tip: SCSI Probe, a free utility available from most on-line services and user groups, can be helpful when sorting out a SCSI ID scuffle.
Problem: When using a screen saver, "How Computers Work” menus don’t always look or behave quite like they should.
Solution: Some screen savers are not compatible with "How Computers Work.” If your Mac suffers from misbehaving menus, disabling your screen saver should do the trick.
Error Messages
Message: “Last task could not be completed because memory ran out.”
Solution: If you’ve been running "How Computers Work” for only a few minutes when this message appears, the Mac is probably telling you that your RAM (memory) configuration is marginal. Though you have just enough to launch the program, there isn’t really enough left over to do anything else. Refer to the section above entitled “Optimizing RAM.” Removing a few system extensions should do the trick.
If, on the other hand, you’ve been running the program for an hour or more when this message graced your screen, it is likely that the system’s volatile memory (RAM) has become too fragmented to carry out the instruction. This can happen in the course of normal computing, especially if you quit out of "How Computers Work” and re-launch or use any other application, including the sample applications. To fix the problem, first check for any active applications. Also make sure the disk cache (Memory Control Panel) is set to the lowest amount. If there are no open applications and the cache setting is low, then restart the Mac to de-fragment the RAM.
Message: “QuickTime installation failed because it was already installed.”
Solution: This message appeared during a restart because you have more than one copy of QuickTime in your System folder. Check (the global Find command works great for this) to remove all but one copy of QuickTime 1.5 from your System folder.
Message: “The How Computers Work CD is not mounted.”
Solution: The “How Computers Work” CD is not mounted. (Even though you may have put it into the drive.)
Even though you copied the application and the sample applications to your hard drive, “How Computers Work” still needs access to the CD. If the CD-ROM was indeed present in the drive when the message appeared, try shutting everything off and checking connections, SCSI termination, INIT configuration (make sure the CD-ROM driver is active) and anything else you can think of. Then power up all attached peripherals (CD-ROM) and try again.
Message: “The movie file ‘We choose the moon’ cannot be found. Without this file the movie cannot play properly.” The user has a chance to either CANCEL or SEARCH.
Solution: This message may appear under System 6.0x when you try to play the movie in “Missions to the Moon,” one of the sample documents in the Microsoft Word Demo. This is because the file, originally created under System 7, employs an embedded alias that System 6.0x can’t see. If this occurs, choose SEARCH and use the dialog box to locate the movie file (pathname: HCW\Sample Applications\Microsoft Word Demo\Movies in Word\We choose the moon).
Message: “How Computers Work requires a color Macintosh.”
Solution: You will get this message anytime you try to view “How Computers Work” on a Macintosh that is incapable of displaying color, such as a first-generation Powerbook or an SE, or a Mac II without a color graphics card installed. The only fix (sorry) is to get a color Mac——or a color graphics card and monitor in the latter example.
Message: “There isn’t enough memory available to play QuickTime™ movies.”
“There isn’t enough memory available to (something).”
"How Computers Work needs more memory to run reliably.”
“(Something) needs more memory to run reliably.”
“There wasn’t enough memory to complete the last task.”
Solution: Most of these messages stem from a low-RAM situation. If they tend to appear after you’ve been running “How Computers Work” for an hour or more, restarting the computer should do the trick. If you still have trouble, follow the steps outlined in the “Optimizing RAM” portion of the Troubleshooting section of this Guide.
If this message appears when you’re trying to print a file such as a Read Me or Guide, refer to the section on “Printing This Guide” in the Read Me document. Hint: the TeachText (or other) application size (“current size”) needs to be increased.
Message: "How Computers Work requires System 6.07 or later in order to use QuickTime™. See the Read Me file for details.”
Solution: You will get this message when you try to run with any system older than 6.07, regardless of whether QuickTime is present in the System folder. Try upgrading your system to at least 6.07 and follow the directions given under “Setting Up Your System.”
Message: "How Computers Work is designed for a 13" monitor.”
Solution: Unfortunately, it not only was designed for at least a 13" monitor—it refuses to run on anything smaller, since important segments of the screen would be deleted.
Message: "How Computers Work requires that the QuickTime™ extension be installed in the System folder.”
Solution: The QuickTime™ extension is either missing from your Extension folder or has somehow been damaged. Try finding it on your hard drive and relocating it to the Extension folder (if it is missing, you can find it on the CD-ROM inside the Support folder). Restart your Mac and try again.
Message: “To run How Computers Work you must reset your monitor to display 256 colors.”
Solution: Open the Monitor Control Panel (Apple Menu) and change the settings to Color/256.
Message: “Mac OS error encountered.” (accompanied by a numeric code such as -28)
“Couldn’t complete the last command because of a Mac OS error.”
Solution: Plainly, your system is confused. Most likely—assuming these messages are infrequent—you are either running "How Computers Work” for a long time at each sitting or your Mac has a very limited amount of RAM available (or both). It is also possible that you have a pesky extension somewhere that is incompatible with "How Computers Work” (we didn’t find any, but we know they must be Out There Somewhere).
If, on the other hand, you’re seeing a lot of these, possibly even across several of your other applications, then you may have system problems. It may be time to optimize your hard drive, or even consider reinstalling system software. Before doing that, try minimizing your extension load as described earlier and restarting your Mac. You might also try replacing QuickTime™ and your CD drivers.
Message: “File not found.”
“I can’t find the asset file. Do you want to show me where it is?”
Solution: "How Computers Work” is having trouble finding a needed file. Unless Elvis has made an unscheduled appearance in the room, this message is most likely the cause of the CD having been removed or rendered inoperative. Check to see if the SCSI cable fell off, or the drive became unplugged, etc.
If the drive is okay, make sure you didn’t copy the "How Computers Work” or sample applications to your hard drive more than one folder deep. Relocate them if necessary to the root level of your hard drive. Then restart and rebuild the desktop (hold down the Option+Command keys just before the desktop appears).
Yet a third condition that can summon one of these messages is—believe it or not—a dirty CD. Inspect it closely for heavy fingerprints or smudges. If you find any, get your hands on some cleaning agent intended for CD’s—or just a very clean, damp, soft cloth. Hold the CD using the “spider” method (fingers on all sides of the CD rather than between index finger and thumb) and wipe the disc from the inside edge straight to the outside edge. Don’t wipe in a circular motion around the CD. Reinsert the disc and try again. (“Spider” method—didja like that?)
If problems persist, check SCSI connections, cables and ID numbers and consider replacing CD-ROM drivers (software extensions). Also check system extensions to make sure no loose cannons lurk. If you find any, remove them and restart your Mac.
Technical Support
We are proud of our products and really do shudder to even picture an end user feeling less than joyous after using one of them. Should you experience difficulty operating “How Computers Work” and can’t find the answer in this Guide, contact Warner New Media technical support at (818) 955-9999. Aside from that, take a minute to call or write and tell us what you think of “How Computers Work”—we’d love to hear from you.
