These are all MacOS >= X screenshots. Even on old MacOS there were already such decorative DMGs...

In my school one Mac could read DOS disks (i.e. it has a driver for the FAT filesystem), and another could not. So I draggged the "DOS disk support" from Control Panel onto a floppy (copying it), moved the disk to the computer without the capability, and dragged that icon into its Control Panel. Now both computers could read FAT-formatted disks, and I was amazed that the "driver" installation was that straightforward.