VOGONS


First post, by eddman

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I extracted the content of a DOS 6.22 image file, then created a new blank floppy image with WinImage and injected the files into it. I went into "Boot sector properties" and set it to "MS-Dos 6.22". I even made the label and serial identical to the original DOS image file. I also made sure there are no hidden system files.

I mounted the image in 86box but upon boot it gives the "Non-System disk or disk error" message.

How do you make a floppy to boot properly?

P.S. The initial goal was to make an image with modified files, but I can't even make it work with identical ones.

Reply 1 of 4, by Disruptor

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It's not just the proper boot sector.
MS-DOS also requires some files to be in the right order on the disk.
First put IO.SYS on the disk, then MSDOS.SYS. Third file should be COMMAND.COM, but I'm not sure whether file order is still important with this file.

Reply 3 of 4, by eddman

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Disruptor wrote on 2024-01-28, 11:34:

First put IO.SYS on the disk, then MSDOS.SYS. Third file should be COMMAND.COM, but I'm not sure whether file order is still important with this file.

Never imagined such a thing could be the reason. I injected them in order and now it works.

Reply 4 of 4, by froller

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Disruptor wrote on 2024-01-28, 11:34:

It's not just the proper boot sector.
MS-DOS also requires some files to be in the right order on the disk.
First put IO.SYS on the disk, then MSDOS.SYS. Third file should be COMMAND.COM, but I'm not sure whether file order is still important with this file.

MS-DOS 5.0 boot sector (also used by MS-DOS 6.xx) requires IO.SYS to be the first record in root directory and MSDOS.SYS to be the second.
It also requires IO.SYS to be placed strictly at the beginning of disk space. MSDOS.SYS can be placed elsewhere on the disk.
No requirements on location of COMMAND.COM.

So if boot sector is correct you can erase everything from the disk and copy IO.SYS then MSDOS.SYS and then everything else and it should boot.

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