What's required for a Mac OS 8 CD to be bootable?

January 13, 2006 8:51 AM

What's required for a Mac OS 8 CD to be bootable?

Some time ago, I bought a G3 Kanga PowerBook. It was cheap and seemed to be a good deal. It turned out to be a refurbished machine, but that's not the problem. It didn't come with an original Mac OS installer but with a disk that the vendor had burnt. The disk has the installer for Mac OS 8.5 on it but it won't boot.

As far as I understand, all that needs to be on a Mac OS so that it's bootable is a System Folder containing the necessary files like the Finder. All that is here but the disk still doesn't work.

Are there magic or hidden files that need to be present, like an MS-DOS boot disk?

posted by Grinder to computers & internet (12 comments total)

it needs to be blessed, which you can't do once it's burnt.
posted by bonaldi at 8:59 AM on January 13, 2006

When you burn it, you need to say that it's a bootable CD. You can probably copy the CD to an external HD and boot off it though. That might be worth a shot. You may also be able to burn it again, but this time mark that it's to be used to boot.
posted by chunking express at 9:01 AM on January 13, 2006

"Blessing" the system folder, by the way, consists of altering the boot block so that it knows the ID of the system folder. The reason this is necessary is that the system folder on a "classic" Mac OS disk needn't be called "System Folder." It might be named in another language besides English, for example. So the bootloader was designed not to care what it's called but rather to locate it by ID. The easiest way to bless a system folder using "classic" Mac OS is to move the Finder out of it, then back in -- the running Finder will say "ah, here is a Finder and a System file in the same folder, must be the system folder" and bless it. Mac OS X has a bless command-line tool that can do the blessing. When burning a CD, most burn software will either automatically find the system folder and alter the boot blocks on the resulting CD accordingly, or else there is a checkbox to make it do this (this is how Toast does it).
posted by kindall at 9:34 AM on January 13, 2006

So if I copy the files to a hard disk, copy them onto a blank CD and take the Finder out of the System Folder and then put it back in, it should work OK?

Can I do this on a Mac OS X machine? The only CD burner I have easy access to is running X, but I can get access to one on a machine running Mac OS 9 if needs be.
posted by Grinder at 9:42 AM on January 13, 2006

I think you'd need to do this under Mac OS 9. It was an option when you burnt CDs with Toast. I'm not sure if you can still burn pre-OSX bootable CDs with the new version of Toast. I'm pretty sure you can't using the Finder in OS X. If you have an external HD, I think installing from that might be easiest.
posted by chunking express at 11:09 AM on January 13, 2006

Hmmm. Not 100% sure if that'll work with a disk image (which is what you're doing when you "copy them to a blank CD") or with Mac OS X (that's probably the more important consideration, as Mac OS X wants the System folder to be named "System"). On Mac OS X I'd try the command-line tool, bless -- see "man bless" for details.
posted by kindall at 11:09 AM on January 13, 2006

What I want to do (but didn't make clear originally) is to have a bootable installer CD to hand in case anything happens to the PB HD. (At the moment it's working fine.)

This PB won't run X so it will have to be a Mac OS 8 disk. I'll try it on X and if that fails, I'll get to the OS 9 machine when I can.

I don't have access to Toast. Is that liable to be a problem?

Thanks to everyone for the helpful answers.
posted by Grinder at 12:55 PM on January 13, 2006

LowEndMac has a lot of info and resources for users of older macs. The maillists are good. There's one for G-Books, and i think another for legacy OS versions.
posted by neuron at 8:00 PM on January 13, 2006

I don't have access to Toast. Is that liable to be a problem?

Nah, if you can bless the system folder on the disk image of the CD before you burn it, which you should be able to using the command line "bless" if not the Finder, it should work fine.
posted by kindall at 9:25 PM on January 13, 2006

Thanks again. I'll give it a go.
posted by Grinder at 1:17 AM on January 14, 2006

You should try to upgrade it to OS 9.
posted by joeclark at 3:33 PM on January 14, 2006

I would agree. OS 9 was really amazing.
posted by chunking express at 9:28 AM on January 16, 2006