Tells the real processor type (not emulated 窶 see 窶湾roc窶) on the machine.
Selector always present on PowerMacs. On 680x0 machines, it adopts a numbering scheme different from 窶湾roc窶 selector (but a 窶彙ug窶 in Quadra 660AV/840AV ROMmakes it follow the same scheme!).
