I accidentally deleted my previous version of DOS on my IBM model 8525. I was messing around with it, not knowing much of DOS, and now I'm back to using "IBM BASIC".

Would I be able to install DOS 6.22 straight from BASIC, or do I need an even earlier version of BASIC to install DOS version 6.22? I do not have any other DOS version except 6.22.

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    So are you saying if there is nothing else installed onto the computer except BASIC, if I put the DOS 6.22 install floppies into the computer, it will install DOS 6.22? I was just wondering if I needed a previous version of DOS to install a newer version. Thanks!
    – Ozzy Films
    Commented Apr 20, 2018 at 15:48
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    Not 100% sure about the PS/2 ... but the original 5150/5160 had a ROM basic but got booted to DOS from a floppy. Commented Apr 20, 2018 at 18:16
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    @rackandboneman, I've used ROM BASIC on a few PS/2s (8550, 8560, 8580) when there was no DOS on the hard drive (or no floppy disk inserted).
    – Kaz
    Commented Nov 1, 2019 at 20:18

1 Answer 1


Well, a PS/2 Model 25 got only a floppy drive, so if you deleted the DOS on your only system disk, you might be out of luck. If there is a hard disk, where the DOS files got deleted, then boot from a Floppy with DOS. This now gives two options (assuming the HD got detected and is accessible):

  1. Use the Undelete utility to recover the files or
  2. Copy the missing files from the FD onto the HD.

It all of course, depends on what got deleted.

Another way would be running the install disks. They should detect if the HD is already formatted before making any further damage and thus asks something like "Continue to replace existing DOS".

Either way, you need a DOS system floppy to do so.

Any yes, of course one could do it from BASIC, but that's a rather masterly task - not recommended for people that need to ask about :))

  • If OP is having system disks to boot from, he may try using "undelete" command to restore files just deleted.
    – Anonymous
    Commented Apr 19, 2018 at 16:42
  • Good point. Let's add it.
    – Raffzahn
    Commented Apr 19, 2018 at 16:45
  • Would i be able to install DOS 6.22 if i just inserted the disks? Would an installer start for DOS 6.22? The only thing my IBM is running now is BASIC, so i wasn't sure if i could skip from BASIC right to DOS
    – Ozzy Films
    Commented Apr 19, 2018 at 18:11
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    @OzzyFilms Assuming the PS/2 25 works like original PC, XT, etc. (which I am pretty sure was the case, but I don't recall ever using a 25, just 30, 50, etc. and always with a hard disk), the BASIC you see is in ROM. A floppy or hard disk boot will override - it only goes to BASIC in ROM if nothing else will boot. Commented Apr 19, 2018 at 18:35
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    @OzzyFilms - a DOS boot disk will boot into a working DOS system without needing to install anything. The first disk in the DOS 6.22 install disk set is a boot disk. You can exit the default installation process into a command prompt by pressing F3, I believe. You can then attempt to recover the system using "undelete" as suggested, or potentially fix an unbootable but otherwise present system using "sys a: c:".
    – Jules
    Commented Apr 21, 2018 at 4:44

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