5.00 Operating System DOS Microsoft MS-DOS 5.00 (360K Disk 1) MS-DOS 5.00 (360K Disk 2) MS-DOS 5.00 (360K Disk 3) MS-DOS 5.00 (360K Disk 4) MS-DOS 5.00 (360K Disk 5) MS-DOS 5.00 (720K Disk 1) MS-DOS 5.00 (720K Disk 2) MS-DOS 5.00 (720K Disk 3)