> On Monday, February 17, 2003, at 08:35 PM, Kevin Stevens wrote: >> Perhaps someone more knowledgeable will respond, but I still think >> you've >> encountered an architecture limitation. > > to begin with, Macs use OpenFirmware rather than OpenBoot. the > difference is rather fine, but in essence, OpenBoot is the Sun-branded > proprietary version of their own OpenFirmware property. > > as explained to me by someone at Apple... OpenFirmware has to bootstrap > certain things in a specific order. enabling the ATA controller, the > I/O controller, on up to actually loading the OS into RAM and finally > executing code on the processor. > > when the OS loads is semi-arbitrary, and has to do with what the OS > requires in order function, rather than hardware considerations. an OS > that requires a protected memory scheme, for instance, has to load code > in to the execution pipeline very early in the boot process. OS X > requires this, OS 9 does not.
;) > for OS 9, it's just fine to wait until > much later in the boot process to load any OS-specific code. on the > 8GB-limited machines, the firmware itself can access data in the first > 8GB without actually having to load the ATA controller code from the > BootROM. > > why is all of this exposition important? > > loading the ATA controller code and initializing advanced features of > the chip (and thus, allowing access to the disk beyond the 8GB limit) > happens too late for the bootstrapper to still load OS X. it's NOT, > however, too late to load OS 9. Ah. Thanks for the detail. KeS -- G-Books is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Check our web site for refurbished PowerBooks | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> G-Books list info: <http://lowendmac.com/lists/g-books.html> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/g-books%40mail.maclaunch.com/> --------------------------------------------------------------- >The Think Different Store http://www.ThinkDifferentStore.com ---------------------------------------------------------------
