The MacBook family was first introduced in May 2006 and replaced the iBook as Apple's consumer laptop.

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Why does my MacBook only start when pressing 6 and 4 keys?

I have this lovely little Macbook 1.1 that only responds to a startup when I hold the the power button down for 5 seconds and then tap the button again while pressing 6 and 4 keys down (for 64-bit mode) or in Target Mode. Safe Mode is not available.

My vintage laptop took a bellyflop on a basement floor as I was on my way out the door for a road trip.. The machine was in Sleep Mode when it fell . When I opened the cover, the screen returned, but I got this little Mac "ditty":three tones followed by two tones and then another three tones. I shut the laptop down and restarted it and it booted with the same pattern of notes played again. I restarted again in Safe Mode and it booted OK. I shut it down and reset the NVRAM and the notes stopped playing on startups which was reassuring. I was able to get it going in Safe Mode for several more restarts, but after two days, the Macbook stopped recognizing Safe Mode and I began to receive Kernal Panic Warnings at startup ('unable to find ACPIPlatform'). I reinstalled the OS using Target Mode. but there was no improvement. I reset the NVRAM again and reset the SMC. It booted normally once and then resumed its fickle dormant state.

I put it in Target Mode and tested and retested the hard drive and the drive passed OK. I did a RAM Check (with memtest) and and that was OK. At that point, I noticed that the machine was not shutting down properly and was depleting the battery. Suspecting the SMC, I did another SMC reset which didn't fix things.

Now here's a funny thing: after much trial and error, I found that I can often restart it after an SMC reset by holding down the 6 and 4 keys. I understand that a Core Duo is not a true 64-bit system but, still, my little startup trick works (more often than it doesn't) . Once started, my trusty MacBook works 'Just Swell' - like the Olden Days- all applications opening etc. But once my hard drive goes to sleep, or, I shut her down. I'm back to square One : SMC reset and hold down 6 and 4...

Does anyone have any ideas about curing this bug?? Is it the SMC? Could it be that somehow the one of the cores of the CPU that is involved with startup is damaged?

I took it in to see the Mac 'Genius' and he was at a loss. very disappointed there.

Update (11/03/2015)

Well, I have tried the external boot and the MacBook hard drive booted up fine. So I don't think the drive is bad. I also turned the AirPort off followed your advice to check the battery and the battery is OK.

Also, I reset startup to safe mode using the Terminal command, but it still wouldn't boot into safe mode. I then tried the sudo NVRAM command to set it up for 64 bit mode to see if I could skip the ritual of pressing the 6 + 4 keys, but there was no change - still had to press the keys! I noticed that the sleep light is not glowing when the lid is shut. I checked the sleep settings, but they were set up correctly. I am baffled.

Now I'm wondering if pressing the 6 and 4 keys has some effect on the start up other than setting up the 64 bit kernel. After all, the macbook is a Core Duo (not a Core 2 Duo) so it doesn't accept the 64 bit kernel, right?

Kevin

Answered! View the answer I have this problem too

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I think you update gave us the needed clue here! You are trying to run the newer OS than what the system can support. I think you'll need to make a decision here: Go back to the correct OS your system supports (OS X 10.6 Snow Leopard) or Upgrade your system to one that is able to support the newer OS-X OS's. Using a thunker (software that allows one to run 64bit code on a 32bit CPU based system) or enabling developer code which was put in place for the transition to 64bit coding, is not wise as either can stop working as Apple updates its OS.

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Well, that makes sense, but I am running Snow Leopard (10.5.8). Is there some way that the 64 bit over-ride is bypassing the SMC protocols?

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Did you replace the PRAM battery?

Often these older systems encounter a strange funk as the PRAM settings are messed up as the battery which holds the data within it is unable to hold its integrity. Here's the IFIXIT guide for one of the MacBooks: MacBook Core 2 Duo PRAM Battery Replacement.

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Thanks Dan,

But I don't think it's the PRAM battery. For one thing, I am not loosing my date and clock settings when the system crashes at shutdown. When i finally do get it restarted the correct settings are still there.

- K

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With the internet available the clock & date & time stamps are less of a clue. The Mac OS now syncs to the Apple Time server during boot up which will mask the issue. If you disconnect your internet access (wired or WiFi) and start up the system then create a text document or something, check the finders date & time setting of the file if its off then its the battery. These batteries do have a lifespan so if you haven't replaced it since you go your system its time anyways to do it.

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What happens when you boot up under an external bootable drive (ideally FireWire)? Hold the Option key when your start the system to gain access to the boot manager then select the external.

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Sounds like the hard drive is going out due to the drop and the sections that have 64bit work ok and that is why you are able to boot into it.

I would try booting to a bootable OS or trying another drive. Which ever is easier. Should confirm that it is indeed the drive.

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Thanks, Michael, for the quick response! I did a hard drive swap and the drive is OK.

Could this be a SATA cable problem? Could a cable get injured in a fall?? The drive is a SATA2. Or a faulty SMC? As I said earlier, all works fine until shutdown- then it needs a forded shutdown and restart using the 6 and 4 keys for 64 bit override. So weird.

Cheers,

Kevin

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I suppose the cable could have been damaged, I have seen crazier things!

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kevin will be eternally grateful.
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