Resolved How do I manually change the startup disk to boot to os x on an iMac g3 400mhz?

longboarder

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Original poster
Nov 15, 2016
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Yesterday an annoying and almost saddening issue happened. I was playing some games like quake 2 and Alice on my vintage iMac g3 and I decided to boot up the game MDk. I realized It was very buggy to play in classic mode so I decided to switch the startup disk to os9, something I hadn't done since I upgraded the hard drive. I remember while swapping this that os9 supports less storage than os x supports but I thought nothing of it at the moment (note you I was using a 250 GB Maxtor with a 90 (operating system), and 30 GB (games) partition set up that worked just fine). Now comes the problem at hand. The computer will only show a question mark with a grey folder. Even after I reset the ram on startup it won't go back. Since I can't change the startup disk now all I want to do is get back to os x. Obviously that's not going to be easy considering you can't change the startup disk on bootup but then I found a way that may lead to a possibility. I have a computer that runs Linux and an ide to USB adapter handy on me and all I'd need to do is plug that into my computer and figure out what values startup disk modifies. This is where I need your guys help. What files and values do I have to modify to get back into os x? Thanks and regards,
Thomas
 

z970mp

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Jun 2, 2017
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Hold down Cmd + Opt + O + F at the chime. You will boot into Open Firmware. Enter 'multi-boot'.

Try each option until you get into OS X. Once you do, you can use Startup Disk to naturally boot back into OS X.
 

longboarder

macrumors newbie
Original poster
Nov 15, 2016
19
3
Hold down Cmd + Opt + O + F at the chime. You will boot into Open Firmware. Enter 'multi-boot'.

Try each option until you get into OS X. Once you do, you can use Startup Disk to naturally boot back into OS X.
thats where the problem lies...It cant get into os 9 to change the startup disk in the first place. I was able to get into openfirmware which is good so I am getting closer. What I need to figure out is how I can boot the os x kernel through the openfirmware terminal....I coild modify a file personally but Now that im able to access openfirmware it does remove a step
 

DearthnVader

macrumors 65816
Dec 17, 2015
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Red Springs, NC
thats where the problem lies...It cant get into os 9 to change the startup disk in the first place. I was able to get into openfirmware which is good so I am getting closer. What I need to figure out is how I can boot the os x kernel through the openfirmware terminal....I coild modify a file personally but Now that im able to access openfirmware it does remove a step
boot hd:,\System\Library\CoreServices\:tbxi
 

longboarder

macrumors newbie
Original poster
Nov 15, 2016
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3
okay I tried it on all 3 partitions and it game me the stupid mac-parts: bad partition cant open error....is there any way to bypass that error like with a force command or something like that? Im assuming this error is being caused by the 250 gig hard drive
 

DearthnVader

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Dec 17, 2015
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Red Springs, NC
okay I tried it on all 3 partitions and it game me the stupid mac-parts: bad partition cant open error....is there any way to bypass that error like with a force command or something like that? Im assuming this error is being caused by the 250 gig hard drive
Try and get a directory of each partition.

Code:
dir hd:3,\
dir hd:4,\
etc....
If you can't find a file system, then your drive is bad or corrupt, and you will have to try and reformat it( with OS 9 Drivers if you want to boot OS 9 ).
 

longboarder

macrumors newbie
Original poster
Nov 15, 2016
19
3
Try and get a directory of each partition.

Code:
dir hd:3,\
dir hd:4,\
etc....
If you can't find a file system, then your drive is bad or corrupt, and you will have to try and reformat it( with OS 9 Drivers if you want to boot OS 9 ).
I found it on hd10. Now when I load it I get a different error can't open hd:10,\System\Library\CoreServices\:tbxi. Could it be because It isnt 10.4 but rather 10.2? Would that mean I have to do a different command?
[doublepost=1568733565][/doublepost]YES!!!!! I GOT IT!!!! boot hd12 boot ****ing hd 12!!!!! halleluyagh!!!! dude thank you so much!!!You just saved me so much money and time im so happy rn i could cry!!!thank you thank you thank you thank you thank you
 

DearthnVader

macrumors 65816
Dec 17, 2015
1,014
5,265
Red Springs, NC
I found it on hd10. Now when I load it I get a different error can't open hd:10,\System\Library\CoreServices\:tbxi. Could it be because It isnt 10.4 but rather 10.2? Would that mean I have to do a different command?
[doublepost=1568733565][/doublepost]YES!!!!! I GOT IT!!!! boot hd12 boot ****ing hd 12!!!!! halleluyagh!!!! dude thank you so much!!!You just saved me so much money and time im so happy rn i could cry!!!thank you thank you thank you thank you thank you
No trouble, glad you got it going again.

The ATA bus in your iMac G3 is likely ATA33 or ATA66 and can't address drives larger than 128Gb. Partitioning the drive with partitions less than 128Gb likely has it working, but it may not work as expected.

I think Intech Hard Disk Speed Tools could setup a special partition table to allow large drive support on older ATA Buses that didn't support 48bit Logical Block Addressing.
 

longboarder

macrumors newbie
Original poster
Nov 15, 2016
19
3
No trouble, glad you got it going again.

The ATA bus in your iMac G3 is likely ATA33 or ATA66 and can't address drives larger than 128Gb. Partitioning the drive with partitions less than 128Gb likely has it working, but it may not work as expected.

I think Intech Hard Disk Speed Tools could setup a special partition table to allow large drive support on older ATA Buses that didn't support 48bit Logical Block Addressing.
That'd be nice so I can utilize that extra 90gb that doesn't show up
 

DearthnVader

macrumors 65816
Dec 17, 2015
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Red Springs, NC
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