Parameter Random Access Memory

PRAM stands for Parameter RAM. The Parameter RAM is a portion of RAM that holds key information about your Mac that's needed for starting it up and keeping track of certain settings. In other words, the PRAM keeps track of stuff like your clock's information and control panel settings. Some settings stored in the PRAM include: settings in the Monitors control panel, the Time and Date control panel, the General Settings control panel, the AppleTalk control panel, and the Startup Disk control panel.

PRAM Problem Symptoms:

1. Your Mac may produce unexplainable errors. If any of the errors deal with settings in the following control panels: Monitors, Time and Date, General Settings, AppleTalk, or Startup Disk; the PRAM may have become corrupted and/or the PRAM battery may be dead.
2. The date and time are set wrong.
3. You can't print, connect to the internet, or use an external hard drive. In combination with the problems listed above, the problem suggests that the PRAM is corrupted and/or the PRAM battery is dead.
4. The color scheme on your Mac is wrong and/or your monitor is set to the wrong resolution during startup.
5. You get a startup error such as a Sad Mac or the blinking disk icon. In addition, you can't get around this error by booting up from a CD-ROM (holding down the "C" key) or starting up from a secondary drive (hold down the "Open-Apple, Option, Shift, Delete" keys). This problem suggests that the PRAM is corrupted.
6. Your Mac won't start up, period. When you turn your Mac on, the Happy Mac appears; but that's all that happens. You can't get past this point. A normal PRAM zap will fix your Mac's corrupted PRAM.
7. After you turn your Mac on, nothing happens. Everything seems normal, but nothing appears on the monitor. This problem means that the PRAM battery has gone dead. (As a short-term fix, you can turn your Mac on, turn it off, and turn it back on again. With any luck, your monitor will work and your Mac will function normally.)

How to Fix PRAM Problems:

Fixing PRAM problems is fairly easy. In most cases, the problems listed above can be fixed by doing one of two things:

1. Zap the PRAM. Zapping the PRAM simply means that you are resetting the PRAM to factory settings. Of course, this also means that you will lose settings in the following control panels: Monitors, AppleTalk, General Settings, Startup Disk, and Time and Date. Zapping the PRAM fixes most of the problems listed above, however, in some cases, you may need to replace the PRAM battery.
   To zap the PRAM:
   1. Restart your Mac.
   2. Immediately hold down the keys: Open-Apple, Option, P, R (all at the same time).
   3. Keep the keys held down until you hear the startup chime three more times.
   4. Release the keys.
2. Replace the PRAM battery (See below). If zapping the PRAM doesn't fix the problem, or only fixes the problem once; you may want to replace your Mac's PRAM battery. The PRAM battery is the power source in your Mac that maintains the PRAM's settings while your Mac is turned off.