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rpangrazio's picture
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Joined: 2009 Aug 27
Technical info on Mac OS Rom file for new world macs

I am looking for any technical information for the ROM file for new world Macs. This is the Mac OS ROM file that resides inside of the System folder on any "New World" PPC's. I know the actual ROM or BIOS is an OpenFirmware implementation, and I can find tons of information about that. Any information would be greatly appreciated.

About all I know is that it is a CHRP script that contains a routine that determines information for Mac OS and passes it to the system as it starts. It also contains a copy of the Macintosh Toolbox that it loads into RAM.

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bertyboy's picture
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Joined: 2009 Jun 14

I'm sure that the old world ROM files could be opened in ResEdit.

rpangrazio's picture
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Joined: 2009 Aug 27

The old world roms won't tell me much about how the new world roms facilitate booting. Old world roms used open firmware to boot a boot loader in beginning of the disk, like the pc mbr. The new worlds load the Mac OS ROM file straight from disk and use that. I can read the CHRP boot script, but finding information about those scripts is proving difficult.

Balrog's picture
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Joined: 2009 Apr 24

Take a look at the source code for SheepShaver. It includes a routine to unpack the ROM into an Old World-type 4MB ROM.

http://pastie.org/1185703 for the quick-and-dirty CLI unpacker I wrote, using the SheepShaver code.

rpangrazio's picture
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Joined: 2009 Aug 27

Thats great, thanks.