At 11:34 PM -0500 04/01/2003, Mike wrote: >Can someone briefly describe or list chronologically what takes place >during start up/system boot. (Or refer me somewhere that has the >info.) I am specifically interested in what gets power first and how >the SCSI and PCI busses communicate with the system in determining >the connected hardware.
Brief? *snort* Easier to just paste. :) Apply power. Power supply charges capacitors then outputs stabelized dc power. CPU's RUN line is set, and its interrupt line is tapped. The first bootstrap runs from the ROM. It lights up the built-in video circuitry and starts the self-test routine. The self-test checks cpu integrity, rom integrity, ram integrity, and basic mb and i/o bus responses. If it passes, you get a bong. If it fails, you get a cord and/or a sad mac with an error code. <- audio and video error message, just in case one or the other is foo. The first bootstrap initializes the ROM'd drivers for things like the built-in ADB, USB, PCI, SCSI, and ATA buses. Each driver in turn queries its hardware to make sure its alive. The strap then looks for a boot target, seeking in a priority order: floppy, keyboard indication, or PRAM. If it finds one, it continues the boot from there. At this point, if a target is not found, you get a floppy icon with a question mark on the screen. The strap intiates an query loop, walking up and down the buses until it finds something usable. Regretfully, if anything is foo with the PCI or SCSI buses at this point, Apple's boot usually just hangs. Once a target is found, the strap does a temp mount of the drive and loads the full disk driver from a hidden partition. The disk is then dismounted. It then remounts the drive, using the full driver. It loads the big ROM image from the hard drive, if available. Then switches to the secondary bootstrap in the big ROM. The secondary bootstrap loads the first chunk of the System file, initializes the Managers, and switches to the INIT Manager (which loads all extensions) (I think that's the right name). The scri files are loaded from the System Folder. These are specialized system patches that MUST load first first first. eg: System Enablers, Connectix Virtual, etc. Then items in the Extensions folder that contains INIT resources are loaded alphabetically. Some display their icons in the crawl, some don't. Likewise, Control Panels that contain INIT resources are loaded. Then loose items in the System Folder that have INIT resources are loaded. The INIT Manager exits, and the bootstrap loads and runs the Finder. (...The bootstrap hangs around forever and keeps trying to run the Finder, in an infinite loop. That's why the Finder automagically restarts if you kill it!..) The Finder creates the desktop and formally mounts all local disk volumes. As it mounts them, it does a few simple file system checks (which is why the desktop can be slow to display sometimes). WHILE the Finder is starting up, OT's DHCP client triggers. Everything is paused while the DHCP client talks to your DHCP server to get its ip assignment and such. This pause may be less than 5 seconds, but it could be up to two minutes. Then the Finder mounts remote disk volumes. Then the Finder launches all the things in the Startup Items folder. FWIW, - Dan. //What boots up must come down.// -- PCI-PowerMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Sonnet & PowerLogix Upgrades - start at $169 | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> PCI-PowerMacs list info: <http://lowendmac.com/lists/pci-powermacs.shtml> --> 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/pci-powermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
