Old World ROM
Old World ROM computers are the
Details
PCI Power Macs with an Old World ROM contain an Open Firmware implementation, and a copy of the Macintosh Toolbox as an Open Firmware device. These machines are set to boot from this device by default, thus starting the normal Macintosh startup procedure. This can be changed, just as on New World ROM Macs, but with limitations placed on what devices and formats can be used; on these machines, particularly the early machines like the Power Macintosh 9500, the Open Firmware implementation was just enough to enumerate PCI devices and load the Toolbox ROM, and these Open Firmware revisions have several bugs which must be worked around by boot loaders or nvramrc patches. The Open Firmware environment can be entered by holding the key combination ⌘ Cmd+⌥ Option+O+F while booting.
All Power Macs
On all Old World ROM machines, once Toolbox is loaded, the boot procedure is the same. Toolbox executes a memory test, enumerates Mac OS devices it knows about (this varies from model to model), and either starts the on-board video (if present) or the option ROM on a NuBus or PCI video card. Toolbox then checks for a disk in the floppy drive, and scans all SCSI buses for a disk with a valid System Folder, giving preference to whatever disk is set as the startup disk in the
If a bootable disk is found, the
Since the Old World ROM usually boots to Toolbox, most OSs have to be installed using a
The simplest way to identify an Old World ROM Mac is that it will not have a factory built-in USB port. Only New World ROM Macs featured a USB port as factory equipment.
See also
- BootX (Linux), the standard LinuxPPC boot loader for Old World machines
- Quik (boot loader), a replacement boot loader for Old World PCI systems
External links
- Macintosh: ROM Size for Various Models at the Wayback Machine (archived June 21, 2002)