The second generation of PowerPC-based Macintoshes encompasses all machines with a PCI bus introduced prior to the original iMac, and are collectively referred to by the designations Old World or beige box PowerMacs.

Second generation Power Macintoshes differ from the first generation PowerPC machines due to the inclusion of a PCI bus and the use of Open Firmware to boot the machines. It is the version of Open Firmware installed on the system that separates these machines from the next generation New World machines. These machines are historically significant as they began Apple's move towards allowing the use of many of the same industry standard peripherals as found in most x86-based computers.

While New World Macintoshes all currently use Open Firmware 3.0 or greater, Old World machines used versions ranging from 1.0.5 to 2.4. Unlike OF 3, which can load its parameters from a file on the hard drive, these older versions store their parameters in a ROM chip. This means that, unlike OF 3, OF 1 and 2 have a preset listing of parameters, which can only be modified but never increased. This difference in firmware means that different methods are required in order to load non-Apple Operating Systems on Old World Macs than New World ones.

Machines produced prior to the switch to the PCI bus, such as those which used Texas Instruments' NuBus expansion cards, are not considered to be part of the set of Old World machines. For more information on these machines see the write up on first generation Power Macintoshes.

A chronological listing of second generation Power Macintoshes, along with year of introduction, processor type, and Open Firmware version, is as follows:

All non-Apple clones can considered to be second generation Power Macintoshes, with the exception of PowerComputing's original Power clone and Radius' System 100 and System 81 machines, all of which did not contain a PCI bus and as such did utilise any version of Open Firmware.

Note: Although first generation Power Macintoshes can also be referred to as Old World machines, it is better to refer to them as NuBus machines, rather than risk confusion with their second generation successors

Previous: First generation Power Macintosh
Index: Power Macintosh
Next: Third generation Power Macintosh


  • My own experience fiddling with these things

Thanks to Transitional Man for pointing out that Radius made non-PCI clones

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