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Boot Process for older computers...
Authored by: grotz on Apr 17, '01 11:32:45AM

...also, the boot process for older computers doesn't allow for pressing "option" at startup. Unfortunately, the only Macs that do allow are all of the newer AGP-flavored variety, but I could be wrong. All I know is that hitting option does not work on my B&W G3/450 at home or my iMac (rev. 3?) at work.



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Quickly setting boot device on Mac OS X
Authored by: sabi on Apr 17, '01 10:42:54PM

There are a few Open Firmware variables that control booting. The ones I know get changed (which exact ones depend on your Mac model) are 'boot-device', 'boot-command', and 'boot-args'.

For example, when I change my G4 to boot from OS X, the boot-device is:

boot-device mac-io/ata-4@1f000/@0:13,\\\\:tbxi

Booting from OS 9, it is:

boot-device mac-io/ata-4@1f000/@0:9,\\\\:tbxi

The device names should be pretty self-explanatory. The "9" or "13" is a partition number, and the "\\\\:tbxi" tells OF to look for a file with type 'tbxi' (Open Firmware boot script) in the System Folder. On OS 9, this is the "Mac OS ROM" file; on OS X, it is /System/Library/CoreServices/BootX.

You can use the 'nvram' command to write OF variables to NVRAM from Mac OS X. The syntax is "nvram variable=value". So, for example, to switch to Mac OS 9, I'd type:

% sudo nvram boot-device='mac-io/ata-4@1f000/@0:9,\\\\:tbxi'

(You need to use single quotes, otherwise the backslashes get interpreted by the shell, which is bad. In this forum software, incidentally, you need to use 4 backslashes in your comment to get 1 backslash as output!)

Use 'sudo nvram boot-device' to check that it's set properly. If all else fails, just use System Preferences, which will reset the values to sensible defaults.

You could make a .command file out of this, to be able to double-click it from the Mac OS X desktop. You need to be root to modify NVRAM, which is why "sudo" is used above. I'd like to write a Cocoa wrapper around it at some point, maybe in a couple of weeks when I add the appropriate USB driver support for my keyboard and mouse (no USB Overdrive on X... aargh.)



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Quickly setting boot device on Mac OS X
Authored by: sabi on Apr 17, '01 10:44:40PM

Argh, sorry, there should be only two backslashes there (\\:tbxi). Turns out you need 4 backslashes per backslash in preview, but only 2 in post.

Bug fixes, anyone?



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Don't just copy this!!! It differs from system to system.
Authored by: Anonymous on Apr 18, '01 05:23:25PM
These values can differ wildly based on your drive setup, the revision of the machine, and whether the ROM is new world (everything with AGP) or old world (everything not AGP). Use the nvram -p command in the terminal to find out the differences. Here is a link to a thread at macosx.com where I detail this process. Zach

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Don't just copy this!!! It differs from system to system.
Authored by: sabi on Apr 19, '01 12:16:54AM

That's a much better description, thanks...



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