To put DOS on a non-DOS disk from BASIC, simply open a file called DOS.SYS for output, and then close it. The DOS you booted with will be written to the disk, and you can now boot with that disk. You won\'t be able to get a DOS menu from it -- that part of the operating system is contained in the file DUP.SYS, which must be copied separately. The following commands to install DOS on drive 1 work with Atari DOS 2.0 and 2.5 and MYDOS, and quite possibly with other operating systems too: 100 OPEN #l,8,0,"D1:DOS.SYS" 110 CLOSE #1