This is the original Sider hard drive installer disk. It's a selfbooting GS/OS disk that has all of the Sider hard drive drivers as listed below: SIDER.40 SIDER.90 SIDER.MULTI.OS SIDER.PRO.10H SIDER.PRO.20H SIDER.PRO.D2 SIDER.PRO.NEC40 It also contains the Unidisk 3.5 driver. Other utilities on the disk include Adv.Disk.Util and Backup2.system.