Old World ROM

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.

If a hardware problem occurs during the early part of the boot process, the machine will display the Sad Mac icon with a hexadecimal error code and freeze; on Macs made after 1987, this will be accompanied by the Chimes of Death sound.

PCI Power Macs can be configured to boot into Open Firmware, allowing the firmware to load a boot loader directly, or they can use a specially-prepared floppy disk to trick the Toolbox into loading a kernel (this is used for Linux installation floppy images).

The simplest way to identify an Old World ROM Mac is that it will not have a factory built-in USB port.