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DISCUSSION Purpose of a Clean Installation ------------------------------- A normal system software installation modifies and updates the existing System Folder. A clean installation disables the existing System Folder, leaving most files in place, and forcing the Installer to create a new System Folder. A clean system installation brings the system software back to the standard configuration. This is necessary when system software has been damaged or modified, preventing a normal installation. It is also useful in troubleshooting. Follow these instructions in the order presented. Restart with Disk Tools ----------------------- Shut down your Macintosh computer, insert Disk Tools in the floppy drive, and turn on the computer. At the desktop, the Disk Tools floppy disk's icon should be in the upper-right corner of your screen with your hard disk's icon below it. If the computer ejects the Disk Tools disk, make sure you have the Disk Tools specified for your model Macintosh. Run Disk First Aid ------------------ Disk First Aid can detect and repair problems with a hard disk. 1) Open the Disk Tools disk, and double-click on the Disk First Aid icon. In the window that appears, select the main hard drive. 2) Click once on Verify. Disk First Aid will check your hard disk for any potential problems. If it finds problems, you should let the software repair them. 3) Repeat this procedure for each hard disk attached to the system. 4) When you're finished verifying the hard disks, choose Quit from the File menu to return to the desktop. If Disk First Aid cannot repair a hard disk, you should back up the hard disk and reinitialize it using the appropriate formatting utility for that drive. For Apple SCSI drives, use Apple HD SC Setup. If you have an Apple IDE drive, use Intrneal HD Formatter or Drive Setup 1.0.2. Update Hard Disk Drivers ------------------------ If you do not have an Apple hard drive, or you use third-party software to format your hard disk, do not use the Apple HD SC Setup utility. However, you should contact your hard drive vendor to verify that your formatting software is compatible with system software version 7.5. If you have an Apple SCSI hard drive, you should update the drivers with the version of Apple HD SC Setup that is in the System 7.5 folder, following these steps: 1) Double-click the Apple HD SC Setup icon on the Hard Drive to open it. 2) Click on the Update button. 3) When you're finished, click Quit to return to the desktop. Sometimes HD SC Setup can not update the hard disk driver (indicated by a "dimmed" Update button). Here are some possible causes and solutions: * If a third-party utility formatted your hard disk, you should obtain the latest version of the utility to update your hard drive. * If a version of Apple HD SC Setup more recent than the version on the Disk Tools disk formatted your hard drive, do not update the hard disk drivers. * If an earlier System 6 version of Apple HD SC Setup formatted the drive, it may not have left enough room for the updated driver. You do not have to update the hard disk drivers. However, if you intend to use file sharing or have a Macintosh that can use virtual memory, then you need to back up the disk and reinitialize it with HD SC Setup. This erases the disk, so be certain you back up the hard disk first. * If the driver is corrupt, the Macintosh does not recognize the drive (that is, the drive doesn't show on the desktop when you start from a floppy disk). You may wish to reinitialize it with HD SC Setup. This erases the disk, so be certain you back up the hard disk first. * If the driver was modified with disk compression or security software you may not be able to update the SCSI drive with Apple HD SC Setup. Contact the vendor for any special instructions. * If your internal hard drive is not a SCSI hard drive, but an IDE drive, you should use Internal HD Formatter or Drive Setup 1.0.2. These utilities are available from online services and are able to test and update the drivers on IDE drives. Check Available Hard Disk Space ------------------------------- Be sure you have at least 21MB available on the hard disk where you plan to install the system software. Open the hard disk's window. Open the Views control panel and select "Show disk info in header." The amount of available disk space appears in the upper-right corner of any open window. If there's less than 21MB available, you'll need to delete some unnecessary files by moving them to the Trash. Choose Empty Trash from the Special menu, and you will have more disk space available. Also you can copy files onto floppy disks or other media before moving them to the Trash. Performing a Clean Install -------------------------- 1. Start up the computer while holding down the Shift key until you see the message "Welcome to Macintosh, Extensions Off." 2. Double-click the Installer located on the Hard Drive. Pass through the Welcome to System 7.5 dialog box. 3. Check the destination drive and make sure the Hard Drive is selected. 4. Press the Command-Shift-K keys simultaneously. You are presented with a small dialog box with two selections: - Update existing system folder - Install new system folder For a clean install, select Install new system folder. This installs a new system folder and renames your current folder to "Previous System Folder". After performing a System 7.5 Clean Install, when About This Macintosh is selected under the Apple menu, it no longer displays the specific Macintosh name. Instead, it displays only "Macintosh", "Macintosh Powerbook", or "Power Macintosh" depending on which system it is running on. If System 7.5 is installed over an existing system (pre 7.5), it retains the specific Macintosh name for the About This Macintosh window. This holds true for future Macintosh computers also. Restart Your Computer --------------------- Choose Restart from the Special menu. The system automatically ejects the Disk Tools disk, and it should boot on the Hard Drive normally. Verify Problem Resolution ------------------------- After performing a clean installation, verify that you resolved the problem before adding anything to the new System Folder. Adding items to the System Folder before resolving your problem defeats the purpose of this procedure. Install Non-Standard Items -------------------------- You can now reinstall the non-standard items from the old System Folder (now named "Previous System Folder") such as fonts, screen savers, device drivers, and so on. If possible, you should reinstall these items from their original disks. If the original disks are not available, you may move the non-standard items from the Previous System Folder to the new System Folder. Be careful not to replace anything that is already in the new System Folder. Only move items that are not already in the new System Folder. 1) Open each corresponding folder within the System Folder and the Previous System Folder then compare the contents. 2) Move anything that is not already in the new System Folder and its subfolders from the Previous System Folder and its subfolders. 3) Restart your Macintosh. Troubleshooting Extension Conflicts ----------------------------------- If you have installed any system extensions or control panels, you will probably see their icons line up across the bottom of the screen when you restart. They load into memory at startup time and modify the standard behavior of the operating system. Verify INIT Conflict -------------------- If the Macintosh fails to restart or behaves erratically, you probably have an incompatible or conflicting INIT (also known as a system extension or control panel). To verify this problem, follow these steps: 1) Be sure the Caps Lock key is off. 2) Restart, and after you see the picture of a computer with a smile, hold down the Space Bar key. 3) Release the Space Bar key when the "Extensions Manager" window appears. 4) Select "All Off" in the Sets pull down menu then close Extensions Manager. 5) When the Macintosh is ready, try to recreate the erratic behavior. If the problem no longer occurs, then you have a conflicting extension or control panel. Continue with the steps in the next section. Turn On and Turn Off INITs in System Folder ------------------------------------------- 1) Using the Extensions Manager turn on your Extensions and Controls Panels one at a time. 2) Close the Extensions Manager, and restart the Macintosh. 3) Attempt to recreate the original problem. Repeat steps 1 through 3 for each item in the Extensions Manager until the problem reoccurs. The last item activated in the Extensions Manager is probably the cause of the problem. Final Steps ----------- Verify that your applications are performing normally. If not, refer to the application manual or contact the vendor. When the Macintosh behaves as expected, move the Previous System Folder to the Trash, and choose Empty Trash from the Special menu. Article Change History: 06 Sep 1995 - Reviewed for technical accuracy, corrected minor typo. Support Information Services |
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| Document Information | |
| Product Area: | Mac OS System Software |
| Category: | System 7.5.x |
| Sub Category: | General Topics |
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