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Re: Troubleshooting a hardware issue on a Ti/800
Authored by: macboyrules on Dec 20, '02 10:36:40AM

The Power-on self-test (POST) is a test in the BootROM Firmware that checks the Mac's hardware and RAM when the computer is first turned on and before any OS information is loaded. This test is only performed on a clean start-up, ie after a shutdown, not after a reboot. If there are problems detected, it will ring out "tones" to let technicians know what it has found. One ring means there is no RAM installed/detected. Two beeps means there is incompatible RAM installed. Three beeps means that there was RAM detected, but errors were found testing the RAM. Four beeps means a bad checksum for the BootROM (checksum refers to a value given to the correct orientation of data, and is a numerical expression "correct" data). And five beeps means that the boot block in the ROM is bad.
From the description you gave, and from the tones you heard, I believe that you had corrupt Firmware. It would be interesting to know if you did a Firmware upgrade on your PowerBook (We have a few at work that have been successfully upgraded). I have found that Firmware upgrades are a very tricky thing, and even so much as a slight power spike can cause problems. Of course, because of the nature of the Firmware upgrade, there would be no way for you to know if something went wrong, other than your computer just not booting after the upgrade.

Firmware corruption can cause all kinds of wacky things to happen. And, unfortunately as you discovered, the only "fix" for a corrupt Firmware is to replace your logic board. I'm a bit surprised that your ASP didn't suggest that this might be the cause, but then end result would have been the same anyway.

I hope this shed a little more light on your situation.



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