My Mac won’t boot up at all?

Sometimes pressing the PMU switch on the motherboard wil allow the Mac to boot up. The PMU (or CUDA) switch allows you to reset all motherboard parameters to default factory settings.

For a Mac G4 (PCI Graphics) you need to press the Cuda reset button on the logic board. The Cuda reset button is located to the right of the battery.
Or, reseat the battery, if the above doesn't work...
1. Unplug the computer.
2. Press the Power On button on the front of the unit.
3. Open the side access panel.
4. Remove the battery from the logic board.
5. Wait at least 10 minutes before replacing the battery.
6. Make sure the battery is installed in the correct +/- direction.
7. Reassemble the computer and test the unit.

PowerMac G4 (AGP Graphics/Gigabit Ethernet) - The PMU Chip
The PMU (Power Management Unit) is a microcontroller chip that controls all power functions for the computer. The PMU is a computer within a computer. It has memory, software, firmware, I/O, two crystals, and a CPU. Its function are: Tell the computer to turn on, turn off, sleep, wake, idle, etc. Manage system resets from various commands. Maintain parameter RAM (PRAM), and the real-time clock.

Important: Be very careful when handling the main logic board. Remove the battery when handling the logic board so the PMU is not affected. The PMU is very sensitive and touching the circuitry on the logic board can cause the PMU to stop responding. If the PMU stops responding, the battery life goes from about five years to about two days if the PMU is not reset. The PMU chip is located near the battery. Many system problems can be resolved by resetting the PMU chip. Whenever you have a computer that fails to turn on, follow this procedure before replacing any modules.

Resetting the PMU Chip
The battery and PMU occupy the same location on the edge of the logic board, which is right next to the PCI slots.
1. Disconnect the power cord and open up the casing to gain access to the logic board.
2. Press the PMU reset switch once, do not press the PMU reset switch a second time because it could stop the PMU chip from working properly.
3. Wait ten seconds before connecting the power cord and turning the computer on.
4. If this does not should do the trick, then you may have to replace the battery, but only if the date and time is lost everytime you do a cold boot.

Note: This entire procedure resets the computer's PRAM. Be sure to reset the computer's time, date, and other system parameter settings before doing anything else.

What is the Boot Options screen and how do I use it?

The Boot Options screen is a feature that comes with all G4s, most iMacs, iBooks, Powerbooks and eMacs, and it allows you to override, temporarily, the preferred boot disk. To bring up the Boot Options screen, you need to hold down the Option/Alt key at the very beginning of bootup. The options screen will show you all bootable disks or partitions currently available to you. If you haven’t put a CD in yet, you can put it in the drive at any point, and then click on the circular arrow button to update the list of disks. Note that you cannot choose from multiple systems that have been installed on a single partition, only the currently activated system will show up on that drive/partition.

It may take ten of more seconds for the list of disks to show up at first, so be patient. Once the beachball (thinking mode) has changed to a pointer (arrow), you can choose the disk you want to boot from, by clicking on it’s icon, and then clicking on the arrow button, pointing right. See this picture for an example of this screen.

Why am I getting the Broken Folder, Prohibitory sign (circle with diagonal line through it), or a Kernel Panic screen?

Some of the more common issues that could cause this at boot up are:
1) The Prohibitory or Broken Folder signs mean that the Mac cannot boot from a valid OS X System. So this will mean that either No.2, below, has happened, the System is corrupted or it cannot boot up off this disk/partition because the disk is in need of repairs via a disk repair program. Boot off a System CD and fix the errors on the disk.
2) Renaming or removing/deleting some of the files or folders from the root of the System hard disk will most certainly cause a kernel panic or flashing question mark disk screen. DO NOT move or delete any of these files: mach, mach kernel, mach.sym. Nor should you rename, move or delete any of these folders: automount, Applications, etc, Library, System, tmp, Users and var, from the root of the disk. These can be found at: search.info.apple.com
3) Certain graphics hardware may produce a kernel panic message during startup. These ones are known to Apple: Matrox RTMac Card (see technical doc: 106422) and 128 bit 2D/3D Professional Graphics Card (see technical doc: 106404).
4) Corrupted fonts, most likely MacOS 9 System Fonts, or maybe fonts in OS X’s
Fonts folder.
5) Incompatible third party or damaged Startup Items, found in either the <harddisk>/Library/StartupItems folder, or <harddisk>/System/Library/ StartupItems folder. Rename them from the log-in system prefs window.
6) Auto-dialup may be interfering with log-in items, turn this feature off.
7) Reset the privileges for all System files. Do this via the Disk Utility and it’s First Aid pane.

When I boot up my Mac, all I’m getting is a blue screen with a continuous spinning beach ball, what can I do to get out of this?

There are a number of reasons why OS X will not boot up in this manner:
1) MacOS X will scan your OS 9 System Folder’s Fonts folder, and use them. If any of those fonts are corrupted in anyway, it will cause this hang in OS X. Suggest you remove all fonts in OS 9’s System, until you can discover which one is the culprit - boot into MacOS 9 and open the Suitcase files, and see if an error occurs, if it does, then that file is corrupted, bin it, or move the contents (if OK) into another suitcase file.
2) Boot via either an OS 9 CD or off another partition, and temporarily remove third party items from the <harddisk>/Library/StartupItems and <harddisk>/System/Library/StartupItems folders, and move them to either your User folder, or onto the desktop. If you’re not sure if an item is from third party software, then don’t remove it. Reboot, and see if the blue screen goes away. If it does, then one of those items you removed is at fault, either because it is corrupted or not compatible with your current version of OS X.
3) In some instances, setting auto-dial may interfere with the login process. This option is set in the Networking Control Panel, under PPP Options, then uncheck the Connect automatically when starting TCP/IP applications box.
This setting can be removed from single user mode by removing the preferences file that holds the setting. This will reset all network settings to the OS default set.
a. Start up in Single-User Mode (press and hold the Apple+S key combination during startup until white text appears).
b. Type: mount -uw /
c. Press Return.
d. Type: mv /var/db/SystemConfiguration/preferences.xml preferences.old
e. Press Return.
f. Type: reboot
g. Press Return
4) Reset certain privileges.
a. Start up in Single-User mode, press and hold the Apple+S key combination during startup until white text appears.
b. When the command line appears, type: fsck -y
c. Press Return.
d. Type: mount -uw /
e. Press Return.
f. Type: chmod 1775 /
g. Press Return.
h. Type: reboot
i. Press Return.

Why does MacOS X seem to pause for a long time when booting up?

This can be normally attributed to three things:
Network time-outs - This happens when the computer is checking for a network, but the address in the System Preferences/Network pane is incorrect, and therefore what it is doing is searching for something that does not exist! You will see “initialising network” in the startup procedure for quite a while. Let it do it’s thing, and then once in the Finder, go to the Preferences window and retype in your correct ethernet network settings. If it persists, disconnect the Ethernet cable, and see if the delay goes away. Or switch on any routers or switchers connected to the network.
If you have enabled NetInfo, you may need to temporarily disable it with the Directory Setup application.

Corrupted Startup Disk - Probably caused by a previous crash, where a reboot was required, and this in turn has damaged the directory structure of the hard disk or partition. Suggest you run a disk repair program from CD or off another bootable partition, to iron out the errors on the main system disk.

USB & Firewire hardware - Some external peripherals may not be working correctly, or they have died on you, which could cause the OS to look for something that is no longer available. Best thing to do is to disconnect all devices and reboot your Mac properly, then plug them back in until you find out which one is not working.

MacOS X refuses to bootup, it just hangs on a grey boot screen or gives me a message about a Safe Boot?

Assuming that there is nothing wrong with your Mac, hardware wise, eg. it does not boot from CD, then all you need to do is to fix the hard disk. Usually a crash will cause disk corruption and this needs fixing immediately. There are three ways to do this:
1) Make sure that the current firmware for your computer is installed.
2) All of these files and folders for MacOS X must not be moved, renamed or deleted: Applications, Library, System, Users, automount, mach, mach_kernel, mach sym, etc, tmp, var. Otherwise you’ll have to reinstall OS X again.
3) Boot up via the OS X System Disk, and select Disk Utility from the menu, then repair the disk, or use a third party repair program.
4) Boot up your Mac and immediately hold down the Shift key until the Safe Boot screen shows. Then it will start it’s disk verification and repair routines on the disk. Beware that large hard disks take longer to fix them, so be patient.
5) If you made a small emergency boot partition on your internal hard disk, with OS X or OS 9.2x and has OS X friendly disk repair utilities on it, use them to fix the corruption on your main System disk or partition.
6) You can use the Command Line Interface (Terminal), press the Apple+s keys to repair the disk manually. Then type in this when the hash character appears (#), this is the prompt line. Type in this “fsck -y” without the quotes, to invoke a self repair of the hard disk. If fsck has repaired or altered anything it will return with this message “***** FILE SYSTEM WAS MODIFIED *****”. If it does not show this, then further passes over the disk will be required, so that any missed errors are also fixed.
Remember, MacOS X has gone back to the dark days of having to boot off another disk in order to fix the main System hard disk, so have a bootable CD or another System partition to boot from, when trouble raises it’s head.
7) Disconnect all external ADB, USB, Firewire, SCSI and PCMCIA devices, and boot up. If the problem goes away, then one of the devices is the cause of the bootup failure. You will have to reconnect them one at a time to discover which one is giving your Mac grief. Once you have discovered which one is the culprit, then it may be dead or requires a driver update, especially if you have updated the OS.
8) Disconnect all third party internal RAM and PCI cards. Again go through the process of connecting them one at a time to discover which one is the problem card. You may have to replace the card with a working one, or reconnect it if you have recently installed a new incremental or full version of the OS.
See this picture for details.

How do I copy MacOS X to another disk and still have it bootable?

Use Carbon Copy Cloner (freeware), which will copy all the important files and folders in order for OS X to be bootable - you cannot do this by simply copying over the visible folders of MacOS X, and expect it to work. You can find and download it from: http://software.bombich.com/ccc.html.

Why is the screen grey after I installed OS X (10.1 or later versions)?

You haven’t installed the current firmware update for your Macintosh (G3 or G4 models only). This must be done in OS 9, and it must be run from a writable disk. To get out of this situation, you will have to boot into MacOS 9 via either a System CD or by pressing the Option/Alt key and selecting your OS 9 partition. Download the update from the Software Update control panel or from Apple’s Support web page. You can download the firmware update from here.

I cannot startup from the MacOS X CD/DVD?

1) Inspect the MacOS X CD/DVD, and make sure that the shiny side of the disc is clean, it must be free of muck (no particles, smudges, or other surface abnormalities).
2) Make sure that current firmware is installed - this will optimise your Mac for maximum compatibility with the latest version of OS X that you want to install, or already installed.
3) Disconnect any external peripherals, except for the Apple keyboard and mouse. This includes USB and SCSI devices, as well as PCMCIA cards. Then boot up with the MacOS X CD/DVD.
4) Remove third-party hardware upgrades. This includes upgrades such as memory (RAM) and other PCI cards NOT installed when you bought the Mac. Note: MacOS X does not natively support third-party cards, therefore it is likely to get confused.
5) You're trying to boot from an incompatible system disk, eg. it's made for an Intel Mac and you have a PPC G5 Mac.

Why can’t I get my Mac to boot from any MacOS 9 CDs, or from the installed Classic System Folder?

The most common explanation is that Apple, in it’s infinite wisdom, has decided that all later Macintosh models can only boot into MacOS X. If you need to boot into OS 9, then you will need a dual boot Mac, so that it can boot into OS 9 and OS X.
However, if you can boot into MacOS 9, because you have an earlier Mac, then it could be caused by two or three things:
1) Make sure that the firmware for your Mac has the latest version installed.
2) Zap the PRAM (Apple+Option+P+R keys at bootup), and try again.
3) The version of Classic MacOS, may be a contributing factor. Make sure you’re using MacOS 9.1 to 9.22, preferably the latter.
4) See if you can boot from a MacOS 9 CD via the Boot Options screen. Then go into OS 9's Startup Disk control Panel and reset it to System Folder on the hard disk.
See this picture for details.