I suppose it's nitpicky to point this out, but most higher-end 32 bit x86 cpus since the Pentium Pro directly support up to 64GB of RAM (assuming you could find/build a suitable motherboard). Using more than 4GB of RAM for a single process involves resorting to oddball memory models but PAE demonstrates it's certainly *possible* to have more than 4GB of RAM in a 32 bit machine.
(16 bit Superminis from the 1970's, like the larger versions of the PDP-11 that UNIX was developed on, usually had "similar" address space extensions and programming models to allow the direct utilization of RAM sizes greater than the 64k their word length would imply. The segmentation model used in the original Intel 8086 is another, albeit slightly brain-damaged, example.)
Of course, this has absolutely nothing to do with a Powermac G4, since so far as I know 32 bit PPCs have nothing analogous to PAE...
(16 bit Superminis from the 1970's, like the larger versions of the PDP-11 that UNIX was developed on, usually had "similar" address space extensions and programming models to allow the direct utilization of RAM sizes greater than the 64k their word length would imply. The segmentation model used in the original Intel 8086 is another, albeit slightly brain-damaged, example.)
Of course, this has absolutely nothing to do with a Powermac G4, since so far as I know 32 bit PPCs have nothing analogous to PAE...