[RKDinOKC]

Says it can save tiff files up to 4GB

Part of the reason everything is limited to 2GB is that is the limit of a LOT of OS's files.
The backups from my Mail Server are in 2GB chunks because of that.

On the Mac Disk Images, .dmg looks like a large file (the size of a disk) but they are actually containers that mount like a disk with a bunch of regular sized files.

Seems like with cameras and scanner now making really big files they would update this so they could manage bigger files. I think they is a limit to most programs of what they consider a lot of ram ie 2GB and the file is copied from ram to the disk.

Seem to remember a graphics program from way back that would let you edit graphics much larger than your memory. It loaded chunks into memory and if you zoomed or moved around it would start the disk whirring and redraw. Don't remember what it's name was, don't think it was photoshop though.