>From: "James Dwyer" <[EMAIL PROTECTED]> >Date: Tue, 20 Aug 2002 15:40:44 +0200
>This is just a layman's effort: The computer cannot know if there is a >fireware interface if it doesn't have the right firm-/software to >identify it. Pre-firewire machines must load that information from your >bootdisk, thus cannot boot from a firewire disk it cannot recognize >before booting! Later models recognize firewire from their firmware and >can boot accordingly. > >Did I do okay, all ye critical readers who know more than I? You did great. I would add that the firmware is stored on chips on the motherboard. By analogy, on a bootable SCSI card, there is a memory chip (ROM, EEPROM or Flash) on the SCSI card itself which stores firmware/drivers for the SCSI card. The firmware in that memory chip is read by computer at startup and tells the computer how to operate the SCSI card. The same is true of video cards. It is a part of the PCI standard for the computer to read the firmware on the PCI cards at start up. The Adaptec 2906, in contrast, has no on-board firmware, no memory chip on the card, and it is not a bootable card. One must wait until the OS has loaded extensions (drivers) before the 2906 is operable. The Firewire cards in the Old World machines are in the same boat as the Adaptec 2906. There is no firmware on the card, no memory chips available in which to store drivers. So, as James wrote, the firewire card cannot operate until the machine has loaded the OS from some other source and loaded the extensions which contain drivers for Firewire which tell the computer how to address and operate firewire cards. On newer machines which have Firewire built in Apple has put the drivers for firewire in the ROM chip--or I guess it's in a Flash chip these days. At any rate, the drivers for firewire, the firmware, is stored on a memory chip on the motherboard, so that it is available to the computer as soon as it boots up and so firewire is bootable. In theory, it would be possible to build a firewire card with a ROM or Flash chip on board storing firmware for the card, so that it would be bootable on the Old World machines. I asked Sonnet about this once, and they said Apple wanted too much to license the Firewire OF code that would be necessary. I guess it would be too difficult to write their own. Jeff Walther -- Unsupported OS X is sponsored by <http://lowendmac.com/> Support Low End Mac <http://lowendmac.com/lists/support.html> Unsupported OS X list info <http://lowendmac.com/lists/unsupported.html> 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/unsupportedosx%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
