my friend has acquired an 1987 model of the Apple II GS via salvation army store for only $15 (with printer!). the computer boots up, the monitor works, the disk drive (3.5" floppy) works, and everything seems to be functioning okay. but, it's only booting up from the disk in the disk drive, which is AppleWorks, so theres no GUI OS. or i cant find it. trying to boot up without a disk in the drive just notifies that it is checking the disk. i am a little confused, is my friend missing a required disk to boot up in a Mac OS? it has a mouse, so there must be a GUI somewhere.