On a PowerPC-based Mac like a G4 or G5, you can hold down Ctrl+Alt+[O]+[F] to boot into Open Firmware. Then, if you type reset-nvram followed by reset-all your firmware will be reset and the Mac will reboot, which can deal with some otherwise unexplained booting or stability issues.
Startup modes
There's no easy way to access an Intel Mac's version of open firmware, which is known as EFI, but on all OS X systems you can boot straight into the UNIX heart of your system, bypassing the normal startup procedure in an attempt to solve startup problems.
Be aware that as well as helping, you can unwittingly do great harm to your system from the command line, so if you're brave enough to enter this world, stick to the exact commands.
If you hold Ctrl+[V] during startup you will enter Verbose Mode, which uses text to display what is being loaded during startup. This can help you to identify the point at which a fault may be occurring by seeing where the startup fails. By holding Ctrl+[S] during startup you enter Single User Mode. Here you can run deep level disk checking.
At the command prompt, type /sbin/fsck –fy and the system will check the drive thoroughly, which may take a while. If any errors are found, repeat the command to run the check a second or even third time until it stops reporting problems. At that point, type reboot and press [Enter] and see if that has solved the problem.
A further option, if none of the above methods work for you, is to perform an archive and install procedure. Boot from the OS X install DVD, choose to install OS X and then choose the Archive and Install installation type. This will install a fresh system and 'quarantine' the old one without deleting it.
If you think some element of the system software may be the problem, you can check the box marked preserve users and network settings and this will import your Home folder and personal data and settings. The trick then, if the new system works, is to bring it back up to date without repeating the step that caused the problem in the first place.
As an aside, when major system updates are released it's often advisable to wait at least a few days before installing them and watch for reports on the web to see if they exhibit problems. This way you can save yourself some potential headaches.
How to manage login and startup items
1. Go to your boot drive, Macintosh HD, then navigate to Library > StartupItems. You will see the items your Mac loads during its initial startup phase associated with third-party apps. Since we no longer need the interface driver, it can be deleted, which will speed up booting a little.
2. Go to System Preferences > Accounts > Login Items. Here you can see what is set to load when you log in. It could be that when you installed peripherals like printers, scanners or gaming devices they placed code or applications in here. If you know you no longer need a particular device, you can remove its associated login items.
3. To choose a different startup drive, go to System Preferences > Startup Disk and choose from available local volumes including bootable CDs or DVDs and a Boot Camp partition if there is one. Or, when starting up, hold down [C] to boot from CD/DVD or hold down Alt to bring up the volume selection screen.
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First published in MacFormat, Issue 204
Now read 25 milestones from 25 years of the Mac
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