ntalaec wrote on 2020-11-11, 18:19:

I have some MS-DOS games in floppy disks. I bought some of them time ago. After creating disk images with WinImage, I noticed th […]
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I have some MS-DOS games in floppy disks. I bought some of them time ago.
After creating disk images with WinImage, I noticed that some of them have some files (best scores, saved games...) written from the previous owners.

I would like to erase completely all the data related to these files to obtain a clean image of every disk.

I've done some tests with some disk images and an hex viewer to see the changes.
Deleting the files with WiImage or with MS-DOS DEL command just erases the first character from the file's FAT index and leaves all their contents. WIPEINFO from Norton Utilities fills the FAT entry with E5 20 ... 20 instead of 00 ... 00 and the file contents (in a 1.44 MB disk image this area seems to start at 0x4200) with 00 but, at least in the images created with WinImage, empty contents in this area seems to be filled with F6.

I've also tried SDelete from Sysinternals (Windows only) and TDel from Tsahi Chitin, but these two seems to leave garbage in the FAT entry instead of the same bytes (E5 20 ... 20) that writes WIPEINFO, so it's harder to identify the changes in the hex viewer.
I'm using all these programs in PCem with the floppy images loaded in the emulator.

I could load every disk image in PCem, use WIPEINFO, open the image file in an hex viewer, compare it with the unmodified one and replace all changed values to 00, but is there an easy way to do it?

Anyone knows any software in DOS, Windows (95 or 10) or any option in WinImage to erase all the data related to one file?

Yes. I know a few. But they wipe the whole disk, also.

To get rid of left over files:

DOS: BIGFILE
Windows: WIPEFREE
https://www.uwe-sieber.de/util_e.html

^Both programs create a steadiy growing file. Thus, the OS is forced to delete data that's marked "deleted".

Edit: Please test with a backup copy first, before trying with the real disks.

//Complete wipe of all files//
In Windows: CCleaner has a wiping feature.

In DOS:
- PC-Tools' Compress can defrag a medium and delete empty files.
- S0KILL can delete/overwrite complete media, including track 0.

Bootable:
Acronis DriveCleanser can wipe entire disks.

Thanks for you suggestions, but I think I will use Norton's WIPEINFO.

I have noticed that there's an option where you can specify the ASCII character used to wipe the contents of the file and the sequence used to delete FAT's entry is always the same (same bytes, same length), easy to identify and replace.

The other programs are intended to rewrite the data again and again with random bytes to avoid any remains of the original bytes in the physical media, but this is not necessary with an IMG file.