View Full Version : PROM key combo?

06-05-2001, 10:05 AM
Does anyone know the key combination to reset the PROM after one has changed out the battery on the motherboard? Thanks.

06-05-2001, 10:10 AM
OK someone told me that the command is "COMMAND+OPTION+P+R" when the computer boots. But here's my problem- the screen shows an almost "checkerboard" pattern and will not boot. This machine is our server for our business software and we cannot function without it! It's a C500 603e/240 and was working fine until the time battery died and we replaced it. Thanks.

06-05-2001, 10:19 AM
First, the completely useless piece of information: it is called PRAM, not PROM as in Parameter RAM.

The key combination you were given is correct.

I assume that you mean that when you power up the machine you do not get the friendly Mac chord one normally gets and you simply get a checkerboard pattern on the screen?

Usually a checkerboard pattern at start up indicates a problem with your RAM or VRAM. I would open the machine back up and make sure that you did not bump anything loose while you were replacing the battery. Also make sure you got the battery installed in the proper orientation. The PCI slots on that model are on a riser card and it is possible that the riser card is not properly seated. Also, remove and reinstall any RAM to make sure it is seated properly. Oh, and if there's an L2 cache do that as well. Finally check for any loose cables.

When you get that kind of problem right after working on the guts of the computer, chances are you just knocked something loose somewhere. The trick is figuring out which thing it was.

06-05-2001, 10:52 AM
Yeah I knew it was PRAM but I was corrected... aparently incorrectly. I'm not a MAC person, I have been working on PCs for 10 years, but no one else in the office has experience inside machines.

The machine was giving the chime, but the screen just before the disk icon was distorted and after the hard drive spun up the machine would lock. I pulled everything out and checked for loose connections, and there didn't seem to be any, and just for good measure I reseated the processor. Once I did that I had to do the PRAM key combo a few times, and then after about 4 tries it worked. So we are up and running.

Thanks for the insight.

06-05-2001, 12:57 PM
In order to effectively zap the "PRAM" you need to hold those keys down during the boot, before it gets to any screen.... and hold it thru 3-5 pram chimes, and then let it start up. While you are checking to see what needs to be reseated , you might want to hold the cuda reset switch down for 30 seconds....that will give you the mother of all PRAM zaps....however you will need to reset some of your settings after it boots.

06-05-2001, 04:27 PM
What settings does the PRAM hold exactly? I would think it would be similar to BIOS settings for a PC. Could that effect extentions that are enabled? I wouldn't think so... but then what settings would be effected? I did end up holding down the key combo for a few chimes, and before that I had held the reset switch for probably about 10 seconds. Thanks.

06-05-2001, 09:08 PM
Go here http://til.info.apple.com/techinfo.nsf/artnum/n2238 and scroll to the bottom of the page. One thing not on the list is the clock rolls back to time/date before most of you guys were born, except Louie and me. There may be other items and some of the items on the list don't actually change. k